Reading Comprehension Practice Test 2025 Questions Answers

As any good contractor will tell you, a sound structure requires stable materials. But atoms, the building blocks of everything we know and love—bunnies, brownies, and best friends—don’t appear to be models of stability. Why are some atoms, like sodium, so hyperactive while others, like helium, are so aloof? Why do the electrons that inhabit atoms jump around so strangely, from one bizarrely shaped orbital to another? And why do protons, the bits that give atoms their heft and personality, stick together at all?

We are told that every atom has a tiny nucleus containing positively charged protons and uncharged neutrons, swarmed by a cloud of speedy electrons. We are also told that like charges, such as protons, repel each other with a force that shoots up to infinity as they get closer. Even worse, you can’t get much closer than two protons in the nucleus of an atom. So what’s keeping atomic nuclei from flying apart? Obviously, some other force must be at work inside the atom, something that we can’t detect at our human scale. Physicists call this the “strong nuclear force.” But where does it come from?

In order for this force to account for the binding of protons in the nucleus, it must have certain interesting features. First, it can’t have any sizeable effect beyond the radius of the atom itself, or it would play havoc with the nuclei of adjacent atoms, destroying matter as we know it. Second, it must perfectly balance the repulsive force of electricity at an “equilibrium point” of about 0.7 × 10⁻¹⁵ meters, the average distance between bound protons, in order to create a stable nucleus. Third, it must repel at even shorter distances, or else neutrons (which don’t have any electrostatic repulsion to balance the strong nuclear force) would collapse into each other. The graph shows the behavior of such a force relative to the repulsive electrostatic force.

In 1935, Japanese physicist Hideki Yukawa proposed that the nuclear force was conveyed by a then-undiscovered heavy subatomic particle he called the pi meson (or “pion”), which (unlike the photon, which conveys the electrostatic force) decays very quickly and therefore conveys a powerful force only over a very short distance.

Professor Yukawa’s theory, however, was dealt a mortal blow by a series of experiments conducted at Los Alamos National Laboratory in the early 1990s that demonstrated that pions carry force only over distances greater than the distance between bound protons. The pion was a plumber’s wrench trying to do a tweezer’s job.

Current atomic theory suggests that the strong nuclear force is most likely conveyed by massless particles called “gluons” according to the theory of quantum chromodynamics, or QCD for short. According to QCD, protons and neutrons are composed of smaller particles called quarks, which are held together by the aptly named gluons. This quark-binding force has a “residue” that extends beyond the protons and neutrons themselves to provide just enough force to bind the protons and neutrons together.

If you’re hoping that QCD ties up atomic behavior with a tidy little bow, you may be just a bit disappointed. As a quantum theory, it conceives of space and time as tiny chunks that occasionally misbehave, rather than smooth predictable quantities, and its mathematical formulas are perhaps as hard to penetrate as the nucleus itself.

In line 7, “aloof” most nearly means

As any good contractor will tell you, a sound structure requires stable materials. But atoms, the building blocks of everything we know and love—bunnies, brownies, and best friends—don’t appear to be models of stability. Why are some atoms, like sodium, so hyperactive while others, like helium, are so aloof? Why do the electrons that inhabit atoms jump around so strangely, from one bizarrely shaped orbital to another? And why do protons, the bits that give atoms their heft and personality, stick together at all?

We are told that every atom has a tiny nucleus containing positively charged protons and uncharged neutrons, swarmed by a cloud of speedy electrons. We are also told that like charges, such as protons, repel each other with a force that shoots up to infinity as they get closer. Even worse, you can’t get much closer than two protons in the nucleus of an atom. So what’s keeping atomic nuclei from flying apart? Obviously, some other force must be at work inside the atom, something that we can’t detect at our human scale. Physicists call this the “strong nuclear force.” But where does it come from?

In order for this force to account for the binding of protons in the nucleus, it must have certain interesting features. First, it can’t have any sizeable effect beyond the radius of the atom itself, or it would play havoc with the nuclei of adjacent atoms, destroying matter as we know it. Second, it must perfectly balance the repulsive force of electricity at an “equilibrium point” of about 0.7 × 10⁻¹⁵ meters, the average distance between bound protons, in order to create a stable nucleus. Third, it must repel at even shorter distances, or else neutrons (which don’t have any electrostatic repulsion to balance the strong nuclear force) would collapse into each other. The graph shows the behavior of such a force relative to the repulsive electrostatic force.

In 1935, Japanese physicist Hideki Yukawa proposed that the nuclear force was conveyed by a then-undiscovered heavy subatomic particle he called the pi meson (or “pion”), which (unlike the photon, which conveys the electrostatic force) decays very quickly and therefore conveys a powerful force only over a very short distance.

Professor Yukawa’s theory, however, was dealt a mortal blow by a series of experiments conducted at Los Alamos National Laboratory in the early 1990s that demonstrated that pions carry force only over distances greater than the distance between bound protons. The pion was a plumber’s wrench trying to do a tweezer’s job.

Current atomic theory suggests that the strong nuclear force is most likely conveyed by massless particles called “gluons” according to the theory of quantum chromodynamics, or QCD for short. According to QCD, protons and neutrons are composed of smaller particles called quarks, which are held together by the aptly named gluons. This quark-binding force has a “residue” that extends beyond the protons and neutrons themselves to provide just enough force to bind the protons and neutrons together.

If you’re hoping that QCD ties up atomic behavior with a tidy little bow, you may be just a bit disappointed. As a quantum theory, it conceives of space and time as tiny chunks that occasionally misbehave, rather than smooth predictable quantities, and its mathematical formulas are perhaps as hard to penetrate as the nucleus itself.

The primary purpose of the first paragraph is to

By the time we were old enough to read Hemingway, he had become legendary. Like Lord Byron a century earlier, he had learned to play himself, his own best hero, with superb conviction. He was Hemingway of the rugged outdoor grin and the hairy chest posing with the lion he had just shot. He was Tarzan Hemingway, crouching in the African bush with elephant gun ready. He was War Correspondent Hemingway writing a play in the Hotel Florida in Madrid while thirty fascist shells crashed through the roof. Later, he was Task Force Hemingway swathed in ammunition belts and defending his post singlehandedly against fierce German attacks.

But even without the legend, the chest-beating, wisecracking pose that was later to seem so incredibly absurd, his impact upon us was tremendous. The feeling he gave us was one of immense expansiveness, freedom, and, at the same time, absolute stability and control. We could follow him, limitless his odd enchantment, through all the doubts and fears of adolescence and come out pure and untouched. The words he put down seemed to us to have been carved from the living stone of life. They conveyed exactly the taste, smell and feel of experience as it was, as it might possibly be. And so we began unconsciously to translate our own sensations into his terms and to impose on everything we did and felt the particular emotions they aroused in us.

The Hemingway time was a good time to be young. We had much then that the war later forced out of us, something far greater than Hemingway’s strong formative influence.

Later writers who lost or got rid of Hemingway have been able to find nothing to put in his place. They have rejected his time as untrue for them only to fail at finding themselves in their own time. Others, in their embarrassment at the hold he once had over them, have not profited by the lessons he had to teach, and still others were never touched by him at all. These last are perhaps the real unfortunates, for they have been denied access to a powerful tradition.

Passage 2

One wonders why Hemingway’s greatest works now seem unable to evoke the same sense of a tottering world that in the 1920s established Ernest Hemingway’s reputation. These novels should be speaking to us. Our social structure is as shaken, our philosophical despair as great, our everyday experience as unsatisfying. We have had more war than Hemingway ever dreamed of. Our violence—physical, emotional, and intellectual—is not inferior to that of the 1920s. Yet Hemingway’s great novels no longer seem to penetrate deeply the surface of existence. One begins to doubt that they ever did so significantly in the 1920s.

Hemingway’s novels indulged the dominant genteel tradition in American culture while seeming to repudiate it. They yielded to the functionalist, technological aesthetic of the culture instead of resisting it in the manner of Frank Lloyd Wright. Hemingway, in effect, became a dupe of his culture rather than its moral-aesthetic conscience. As a consequence, the import of his work has diminished. There is some evidence from his stylistic evolution that Hemingway himself must have felt as much, for Hemingway’s famous stylistic economy frequently seems to conceal another kind of writer, with much richer rhetorical resources to hand. So, Death in the Afternoon (1932), Hemingway’s bullfighting opus and his first book after A Farewell to Arms (1929), reveals great uneasiness over his earlier accomplishment. In it, he defends his literary method with a doctrine of ambiguity: "If a writer of prose knows enough about what he is writing about." about he may omit things that he knows and the reader, if the writer is writing truly enough, will have a feeling of those things as strongly as though the writer had stated them."

Hemingway made much the same theoretical point in another way in Death in the Afternoon apparently believing that a formal reduction of aesthetic complexity was the only kind of design that had value.

Perhaps the greatest irony of Death in the Afternoon is its unmistakably baroque prose, which Hemingway himself embarrassedly admitted was “flowery.” Reviewers, unable to challenge Hemingway’s expertise in the art of bullfighting, noted that its style was “awkward, tortuous, [and] belligerently clumsy.”

Death in the Afternoon is an extraordinarily self-indulgent, unruly, clownish, garrulous, and satiric book, with scrambled chronologies, willful digressions, mock-scholarly apparatuses, fictional interludes, and scathing allusions. Its inflated style can hardly penetrate the façade, let alone deflate humanity.

The author of Passage 2 suggests that, in comparison to Hemingway, Frank Lloyd Wright was relatively

By the time we were old enough to read Hemingway, he had become legendary. Like Lord Byron a century earlier, he had learned to play himself, his own best hero, with superb conviction. He was Hemingway of the rugged outdoor grin and the hairy chest posing with the lion he had just shot. He was Tarzan Hemingway, crouching in the African bush with elephant gun ready. He was War Correspondent Hemingway writing a play in the Hotel Florida in Madrid while thirty fascist shells crashed through the roof. Later, he was Task Force Hemingway swathed in ammunition belts and defending his post singlehandedly against fierce German attacks.

But even without the legend, the chest-beating, wisecracking pose that was later to seem so incredibly absurd, his impact upon us was tremendous. The feeling he gave us was one of immense expansiveness, freedom, and, at the same time, absolute stability and control. We could follow him, limitless his odd enchantment, through all the doubts and fears of adolescence and come out pure and untouched. The words he put down seemed to us to have been carved from the living stone of life. They conveyed exactly the taste, smell and feel of experience as it was, as it might possibly be. And so we began unconsciously to translate our own sensations into his terms and to impose on everything we did and felt the particular emotions they aroused in us.

The Hemingway time was a good time to be young. We had much then that the war later forced out of us, something far greater than Hemingway’s strong formative influence.

Later writers who lost or got rid of Hemingway have been able to find nothing to put in his place. They have rejected his time as untrue for them only to fail at finding themselves in their own time. Others, in their embarrassment at the hold he once had over them, have not profited by the lessons he had to teach, and still others were never touched by him at all. These last are perhaps the real unfortunates, for they have been denied access to a powerful tradition.

Passage 2

One wonders why Hemingway’s greatest works now seem unable to evoke the same sense of a tottering world that in the 1920s established Ernest Hemingway’s reputation. These novels should be speaking to us. Our social structure is as shaken, our philosophical despair as great, our everyday experience as unsatisfying. We have had more war than Hemingway ever dreamed of. Our violence—physical, emotional, and intellectual—is not inferior to that of the 1920s. Yet Hemingway’s great novels no longer seem to penetrate deeply the surface of existence. One begins to doubt that they ever did so significantly in the 1920s.

Hemingway’s novels indulged the dominant genteel tradition in American culture while seeming to repudiate it. They yielded to the functionalist, technological aesthetic of the culture instead of resisting it in the manner of Frank Lloyd Wright. Hemingway, in effect, became a dupe of his culture rather than its moral-aesthetic conscience. As a consequence, the import of his work has diminished. There is some evidence from his stylistic evolution that Hemingway himself must have felt as much, for Hemingway’s famous stylistic economy frequently seems to conceal another kind of writer, with much richer rhetorical resources to hand. So, Death in the Afternoon (1932), Hemingway’s bullfighting opus and his first book after A Farewell to Arms (1929), reveals great uneasiness over his earlier accomplishment. In it, he defends his literary method with a doctrine of ambiguity: "If a writer of prose knows enough about what he is writing about." about he may omit things that he knows and the reader, if the writer is writing truly enough, will have a feeling of those things as strongly as though the writer had stated them."

Hemingway made much the same theoretical point in another way in Death in the Afternoon apparently believing that a formal reduction of aesthetic complexity was the only kind of design that had value.

Perhaps the greatest irony of Death in the Afternoon is its unmistakably baroque prose, which Hemingway himself embarrassedly admitted was “flowery.” Reviewers, unable to challenge Hemingway’s expertise in the art of bullfighting, noted that its style was “awkward, tortuous, [and] belligerently clumsy.”

Death in the Afternoon is an extraordinarily self-indulgent, unruly, clownish, garrulous, and satiric book, with scrambled chronologies, willful digressions, mock-scholarly apparatuses, fictional interludes, and scathing allusions. Its inflated style can hardly penetrate the façade, let alone deflate humanity.

Which statement about Hemingway is supported by both passages?

By the time we were old enough to read Hemingway, he had become legendary. Like Lord Byron a century earlier, he had learned to play himself, his own best hero, with superb conviction. He was Hemingway of the rugged outdoor grin and the hairy chest posing with the lion he had just shot. He was Tarzan Hemingway, crouching in the African bush with elephant gun ready. He was War Correspondent Hemingway writing a play in the Hotel Florida in Madrid while thirty fascist shells crashed through the roof. Later, he was Task Force Hemingway swathed in ammunition belts and defending his post singlehandedly against fierce German attacks.

But even without the legend, the chest-beating, wisecracking pose that was later to seem so incredibly absurd, his impact upon us was tremendous. The feeling he gave us was one of immense expansiveness, freedom, and, at the same time, absolute stability and control. We could follow him, limitless his odd enchantment, through all the doubts and fears of adolescence and come out pure and untouched. The words he put down seemed to us to have been carved from the living stone of life. They conveyed exactly the taste, smell and feel of experience as it was, as it might possibly be. And so we began unconsciously to translate our own sensations into his terms and to impose on everything we did and felt the particular emotions they aroused in us.

The Hemingway time was a good time to be young. We had much then that the war later forced out of us, something far greater than Hemingway’s strong formative influence.

Later writers who lost or got rid of Hemingway have been able to find nothing to put in his place. They have rejected his time as untrue for them only to fail at finding themselves in their own time. Others, in their embarrassment at the hold he once had over them, have not profited by the lessons he had to teach, and still others were never touched by him at all. These last are perhaps the real unfortunates, for they have been denied access to a powerful tradition.

Passage 2

One wonders why Hemingway’s greatest works now seem unable to evoke the same sense of a tottering world that in the 1920s established Ernest Hemingway’s reputation. These novels should be speaking to us. Our social structure is as shaken, our philosophical despair as great, our everyday experience as unsatisfying. We have had more war than Hemingway ever dreamed of. Our violence—physical, emotional, and intellectual—is not inferior to that of the 1920s. Yet Hemingway’s great novels no longer seem to penetrate deeply the surface of existence. One begins to doubt that they ever did so significantly in the 1920s.

Hemingway’s novels indulged the dominant genteel tradition in American culture while seeming to repudiate it. They yielded to the functionalist, technological aesthetic of the culture instead of resisting it in the manner of Frank Lloyd Wright. Hemingway, in effect, became a dupe of his culture rather than its moral-aesthetic conscience. As a consequence, the import of his work has diminished. There is some evidence from his stylistic evolution that Hemingway himself must have felt as much, for Hemingway’s famous stylistic economy frequently seems to conceal another kind of writer, with much richer rhetorical resources to hand. So, Death in the Afternoon (1932), Hemingway’s bullfighting opus and his first book after A Farewell to Arms (1929), reveals great uneasiness over his earlier accomplishment. In it, he defends his literary method with a doctrine of ambiguity: "If a writer of prose knows enough about what he is writing about." about he may omit things that he knows and the reader, if the writer is writing truly enough, will have a feeling of those things as strongly as though the writer had stated them."

Hemingway made much the same theoretical point in another way in Death in the Afternoon apparently believing that a formal reduction of aesthetic complexity was the only kind of design that had value.

Perhaps the greatest irony of Death in the Afternoon is its unmistakably baroque prose, which Hemingway himself embarrassedly admitted was “flowery.” Reviewers, unable to challenge Hemingway’s expertise in the art of bullfighting, noted that its style was “awkward, tortuous, [and] belligerently clumsy.”

Death in the Afternoon is an extraordinarily self-indulgent, unruly, clownish, garrulous, and satiric book, with scrambled chronologies, willful digressions, mock-scholarly apparatuses, fictional interludes, and scathing allusions. Its inflated style can hardly penetrate the façade, let alone deflate humanity.

Which of the following best describes how each passage characterizes Hemingway?

By the time we were old enough to read Hemingway, he had become legendary. Like Lord Byron a century earlier, he had learned to play himself, his own best hero, with superb conviction. He was Hemingway of the rugged outdoor grin and the hairy chest posing with the lion he had just shot. He was Tarzan Hemingway, crouching in the African bush with elephant gun ready. He was War Correspondent Hemingway writing a play in the Hotel Florida in Madrid while thirty fascist shells crashed through the roof. Later, he was Task Force Hemingway swathed in ammunition belts and defending his post singlehandedly against fierce German attacks.

But even without the legend, the chest-beating, wisecracking pose that was later to seem so incredibly absurd, his impact upon us was tremendous. The feeling he gave us was one of immense expansiveness, freedom, and, at the same time, absolute stability and control. We could follow him, limitless his odd enchantment, through all the doubts and fears of adolescence and come out pure and untouched. The words he put down seemed to us to have been carved from the living stone of life. They conveyed exactly the taste, smell and feel of experience as it was, as it might possibly be. And so we began unconsciously to translate our own sensations into his terms and to impose on everything we did and felt the particular emotions they aroused in us.

The Hemingway time was a good time to be young. We had much then that the war later forced out of us, something far greater than Hemingway’s strong formative influence.

Later writers who lost or got rid of Hemingway have been able to find nothing to put in his place. They have rejected his time as untrue for them only to fail at finding themselves in their own time. Others, in their embarrassment at the hold he once had over them, have not profited by the lessons he had to teach, and still others were never touched by him at all. These last are perhaps the real unfortunates, for they have been denied access to a powerful tradition.

Passage 2

One wonders why Hemingway’s greatest works now seem unable to evoke the same sense of a tottering world that in the 1920s established Ernest Hemingway’s reputation. These novels should be speaking to us. Our social structure is as shaken, our philosophical despair as great, our everyday experience as unsatisfying. We have had more war than Hemingway ever dreamed of. Our violence—physical, emotional, and intellectual—is not inferior to that of the 1920s. Yet Hemingway’s great novels no longer seem to penetrate deeply the surface of existence. One begins to doubt that they ever did so significantly in the 1920s.

Hemingway’s novels indulged the dominant genteel tradition in American culture while seeming to repudiate it. They yielded to the functionalist, technological aesthetic of the culture instead of resisting it in the manner of Frank Lloyd Wright. Hemingway, in effect, became a dupe of his culture rather than its moral-aesthetic conscience. As a consequence, the import of his work has diminished. There is some evidence from his stylistic evolution that Hemingway himself must have felt as much, for Hemingway’s famous stylistic economy frequently seems to conceal another kind of writer, with much richer rhetorical resources to hand. So, Death in the Afternoon (1932), Hemingway’s bullfighting opus and his first book after A Farewell to Arms (1929), reveals great uneasiness over his earlier accomplishment. In it, he defends his literary method with a doctrine of ambiguity: "If a writer of prose knows enough about what he is writing about." about he may omit things that he knows and the reader, if the writer is writing truly enough, will have a feeling of those things as strongly as though the writer had stated them."

Hemingway made much the same theoretical point in another way in Death in the Afternoon apparently believing that a formal reduction of aesthetic complexity was the only kind of design that had value.

Perhaps the greatest irony of Death in the Afternoon is its unmistakably baroque prose, which Hemingway himself embarrassedly admitted was “flowery.” Reviewers, unable to challenge Hemingway’s expertise in the art of bullfighting, noted that its style was “awkward, tortuous, [and] belligerently clumsy.”

Death in the Afternoon is an extraordinarily self-indulgent, unruly, clownish, garrulous, and satiric book, with scrambled chronologies, willful digressions, mock-scholarly apparatuses, fictional interludes, and scathing allusions. Its inflated style can hardly penetrate the façade, let alone deflate humanity.

On which topic do the authors of the two passages most strongly disagree?

As any good contractor will tell you, a sound structure requires stable materials. But atoms, the building blocks of everything we know and love—bunnies, brownies, and best friends—don’t appear to be models of stability. Why are some atoms, like sodium, so hyperactive while others, like helium, are so aloof? Why do the electrons that inhabit atoms jump around so strangely, from one bizarrely shaped orbital to another? And why do protons, the bits that give atoms their heft and personality, stick together at all?

We are told that every atom has a tiny nucleus containing positively charged protons and uncharged neutrons, swarmed by a cloud of speedy electrons. We are also told that like charges, such as protons, repel each other with a force that shoots up to infinity as they get closer. Even worse, you can’t get much closer than two protons in the nucleus of an atom. So what’s keeping atomic nuclei from flying apart? Obviously, some other force must be at work inside the atom, something that we can’t detect at our human scale. Physicists call this the “strong nuclear force.” But where does it come from?

In order for this force to account for the binding of protons in the nucleus, it must have certain interesting features. First, it can’t have any sizeable effect beyond the radius of the atom itself, or it would play havoc with the nuclei of adjacent atoms, destroying matter as we know it. Second, it must perfectly balance the repulsive force of electricity at an “equilibrium point” of about 0.7 × 10⁻¹⁵ meters, the average distance between bound protons, in order to create a stable nucleus. Third, it must repel at even shorter distances, or else neutrons (which don’t have any electrostatic repulsion to balance the strong nuclear force) would collapse into each other. The graph shows the behavior of such a force relative to the repulsive electrostatic force.

In 1935, Japanese physicist Hideki Yukawa proposed that the nuclear force was conveyed by a then-undiscovered heavy subatomic particle he called the pi meson (or “pion”), which (unlike the photon, which conveys the electrostatic force) decays very quickly and therefore conveys a powerful force only over a very short distance.

Professor Yukawa’s theory, however, was dealt a mortal blow by a series of experiments conducted at Los Alamos National Laboratory in the early 1990s that demonstrated that pions carry force only over distances greater than the distance between bound protons. The pion was a plumber’s wrench trying to do a tweezer’s job.

Current atomic theory suggests that the strong nuclear force is most likely conveyed by massless particles called “gluons” according to the theory of quantum chromodynamics, or QCD for short. According to QCD, protons and neutrons are composed of smaller particles called quarks, which are held together by the aptly named gluons. This quark-binding force has a “residue” that extends beyond the protons and neutrons themselves to provide just enough force to bind the protons and neutrons together.

If you’re hoping that QCD ties up atomic behavior with a tidy little bow, you may be just a bit disappointed. As a quantum theory, it conceives of space and time as tiny chunks that occasionally misbehave, rather than smooth predictable quantities, and its mathematical formulas are perhaps as hard to penetrate as the nucleus itself.

 The question in lines 10–12 (“And why . . . at all?”) indicates

As any good contractor will tell you, a sound structure requires stable materials. But atoms, the building blocks of everything we know and love—bunnies, brownies, and best friends—don’t appear to be models of stability. Why are some atoms, like sodium, so hyperactive while others, like helium, are so aloof? Why do the electrons that inhabit atoms jump around so strangely, from one bizarrely shaped orbital to another? And why do protons, the bits that give atoms their heft and personality, stick together at all?

We are told that every atom has a tiny nucleus containing positively charged protons and uncharged neutrons, swarmed by a cloud of speedy electrons. We are also told that like charges, such as protons, repel each other with a force that shoots up to infinity as they get closer. Even worse, you can’t get much closer than two protons in the nucleus of an atom. So what’s keeping atomic nuclei from flying apart? Obviously, some other force must be at work inside the atom, something that we can’t detect at our human scale. Physicists call this the “strong nuclear force.” But where does it come from?

In order for this force to account for the binding of protons in the nucleus, it must have certain interesting features. First, it can’t have any sizeable effect beyond the radius of the atom itself, or it would play havoc with the nuclei of adjacent atoms, destroying matter as we know it. Second, it must perfectly balance the repulsive force of electricity at an “equilibrium point” of about 0.7 × 10⁻¹⁵ meters, the average distance between bound protons, in order to create a stable nucleus. Third, it must repel at even shorter distances, or else neutrons (which don’t have any electrostatic repulsion to balance the strong nuclear force) would collapse into each other. The graph shows the behavior of such a force relative to the repulsive electrostatic force.

In 1935, Japanese physicist Hideki Yukawa proposed that the nuclear force was conveyed by a then-undiscovered heavy subatomic particle he called the pi meson (or “pion”), which (unlike the photon, which conveys the electrostatic force) decays very quickly and therefore conveys a powerful force only over a very short distance.

Professor Yukawa’s theory, however, was dealt a mortal blow by a series of experiments conducted at Los Alamos National Laboratory in the early 1990s that demonstrated that pions carry force only over distances greater than the distance between bound protons. The pion was a plumber’s wrench trying to do a tweezer’s job.

Current atomic theory suggests that the strong nuclear force is most likely conveyed by massless particles called “gluons” according to the theory of quantum chromodynamics, or QCD for short. According to QCD, protons and neutrons are composed of smaller particles called quarks, which are held together by the aptly named gluons. This quark-binding force has a “residue” that extends beyond the protons and neutrons themselves to provide just enough force to bind the protons and neutrons together.

If you’re hoping that QCD ties up atomic behavior with a tidy little bow, you may be just a bit disappointed. As a quantum theory, it conceives of space and time as tiny chunks that occasionally misbehave, rather than smooth predictable quantities, and its mathematical formulas are perhaps as hard to penetrate as the nucleus itself.

Which of the following best describes the structure of the passage as a whole?

As any good contractor will tell you, a sound structure requires stable materials. But atoms, the building blocks of everything we know and love—bunnies, brownies, and best friends—don’t appear to be models of stability. Why are some atoms, like sodium, so hyperactive while others, like helium, are so aloof? Why do the electrons that inhabit atoms jump around so strangely, from one bizarrely shaped orbital to another? And why do protons, the bits that give atoms their heft and personality, stick together at all?

We are told that every atom has a tiny nucleus containing positively charged protons and uncharged neutrons, swarmed by a cloud of speedy electrons. We are also told that like charges, such as protons, repel each other with a force that shoots up to infinity as they get closer. Even worse, you can’t get much closer than two protons in the nucleus of an atom. So what’s keeping atomic nuclei from flying apart? Obviously, some other force must be at work inside the atom, something that we can’t detect at our human scale. Physicists call this the “strong nuclear force.” But where does it come from?

In order for this force to account for the binding of protons in the nucleus, it must have certain interesting features. First, it can’t have any sizeable effect beyond the radius of the atom itself, or it would play havoc with the nuclei of adjacent atoms, destroying matter as we know it. Second, it must perfectly balance the repulsive force of electricity at an “equilibrium point” of about 0.7 × 10⁻¹⁵ meters, the average distance between bound protons, in order to create a stable nucleus. Third, it must repel at even shorter distances, or else neutrons (which don’t have any electrostatic repulsion to balance the strong nuclear force) would collapse into each other. The graph shows the behavior of such a force relative to the repulsive electrostatic force.

In 1935, Japanese physicist Hideki Yukawa proposed that the nuclear force was conveyed by a then-undiscovered heavy subatomic particle he called the pi meson (or “pion”), which (unlike the photon, which conveys the electrostatic force) decays very quickly and therefore conveys a powerful force only over a very short distance.

Professor Yukawa’s theory, however, was dealt a mortal blow by a series of experiments conducted at Los Alamos National Laboratory in the early 1990s that demonstrated that pions carry force only over distances greater than the distance between bound protons. The pion was a plumber’s wrench trying to do a tweezer’s job.

Current atomic theory suggests that the strong nuclear force is most likely conveyed by massless particles called “gluons” according to the theory of quantum chromodynamics, or QCD for short. According to QCD, protons and neutrons are composed of smaller particles called quarks, which are held together by the aptly named gluons. This quark-binding force has a “residue” that extends beyond the protons and neutrons themselves to provide just enough force to bind the protons and neutrons together.

If you’re hoping that QCD ties up atomic behavior with a tidy little bow, you may be just a bit disappointed. As a quantum theory, it conceives of space and time as tiny chunks that occasionally misbehave, rather than smooth predictable quantities, and its mathematical formulas are perhaps as hard to penetrate as the nucleus itself.

The author’s writing style is particularly notable for its use of all of the following EXCEPT

Just as, before putting up a large building, the architect surveys and sounds the site to see if it will bear the weight, the wise legislator does not begin by laying down laws good in themselves, but by investigating the fitness of the people, for which they are destined, to receive them. Plato refused to legislate for the Arcadians and the Cyrenaeans,¹ because he knew that both peoples were rich and could not tolerate equality. Also, good laws and bad men were found together in Crete, because Minos had inflicted discipline on a people already burdened with vice.

A thousand nations that have achieved earthly greatness could never have endured good laws. Even those nations that could have endured good laws could have done so only for a very brief period of their long history. Most peoples, like most men, are docile only in youth. As they grow old they become incorrigible. Once customs have become established and prejudices inveterate, it is dangerous and useless to attempt their reformation. The people, like the foolish and cowardly patients who rave at sight of the doctor, can no longer bear that any one should lay hands on its faults to remedy them.

There are indeed times in the history of States when, just as some kinds of illness turn men’s heads and make them forget the past, periods of violence and revolution do to peoples what these crises do to individuals. Horror of the past takes the place of forgetfulness, and the state, set on fire by civil wars, is born again, so to speak, from its ashes, and takes on anew, fresh from the jaws of death, the vigor of youth. Such was Sparta at the time of Lycurgus.

But such events are rare exceptions, the cause of which is always to be found in the particular constitution of the state concerned. Such renewals cannot even happen twice to the same nation, for it can make itself free as long as it remains barbarous, but not when the civic impulse has lost its vigor. Then disturbances may destroy it, but revolutions cannot mend it: it needs a master, and not a liberator. Free peoples, be mindful of this maxim: “Liberty may be gained, but can never be recovered.”

There is for nations, as for men, a threshold of maturity before which they should not be made subject to laws. But the maturity of a people is not always easily recognizable, and, if it is anticipated, the work is spoiled. One people is amenable to discipline from the beginning: another, not after ten centuries. Russia will never be really civilized, because it was civilized too soon. Peter the Great had a genius for imitation, but he lacked true genius, which is creative and makes all from nothing. He did some good things, but most of what he did was out of place. He saw that his nation was barbarous, but did not see that it was not ripe for civilization: he wanted to civilize it when it needed only hardening. His first wish was to make Germans or Englishmen, when he ought to have been making Russians; and he prevented his subjects from ever becoming what they might have been by persuading them that they were what they are not. In this fashion too a French teacher turns out his pupil to be an infant prodigy, and for the rest of his life to be nothing whatsoever. The empire of Russia will aspire to conquer Europe, but will itself be conquered. The Tartars,² its subjects or neighbors, will become its masters and ours, by a revolution that I regard as inevitable.

This passage is primarily concerned with

Just as, before putting up a large building, the architect surveys and sounds the site to see if it will bear the weight, the wise legislator does not begin by laying down laws good in themselves, but by investigating the fitness of the people, for which they are destined, to receive them. Plato refused to legislate for the Arcadians and the Cyrenaeans,¹ because he knew that both peoples were rich and could not tolerate equality. Also, good laws and bad men were found together in Crete, because Minos had inflicted discipline on a people already burdened with vice.

A thousand nations that have achieved earthly greatness could never have endured good laws. Even those nations that could have endured good laws could have done so only for a very brief period of their long history. Most peoples, like most men, are docile only in youth. As they grow old they become incorrigible. Once customs have become established and prejudices inveterate, it is dangerous and useless to attempt their reformation. The people, like the foolish and cowardly patients who rave at sight of the doctor, can no longer bear that any one should lay hands on its faults to remedy them.

There are indeed times in the history of States when, just as some kinds of illness turn men’s heads and make them forget the past, periods of violence and revolution do to peoples what these crises do to individuals. Horror of the past takes the place of forgetfulness, and the state, set on fire by civil wars, is born again, so to speak, from its ashes, and takes on anew, fresh from the jaws of death, the vigor of youth. Such was Sparta at the time of Lycurgus.

But such events are rare exceptions, the cause of which is always to be found in the particular constitution of the state concerned. Such renewals cannot even happen twice to the same nation, for it can make itself free as long as it remains barbarous, but not when the civic impulse has lost its vigor. Then disturbances may destroy it, but revolutions cannot mend it: it needs a master, and not a liberator. Free peoples, be mindful of this maxim: “Liberty may be gained, but can never be recovered.”

There is for nations, as for men, a threshold of maturity before which they should not be made subject to laws. But the maturity of a people is not always easily recognizable, and, if it is anticipated, the work is spoiled. One people is amenable to discipline from the beginning: another, not after ten centuries. Russia will never be really civilized, because it was civilized too soon. Peter the Great had a genius for imitation, but he lacked true genius, which is creative and makes all from nothing. He did some good things, but most of what he did was out of place. He saw that his nation was barbarous, but did not see that it was not ripe for civilization: he wanted to civilize it when it needed only hardening. His first wish was to make Germans or Englishmen, when he ought to have been making Russians; and he prevented his subjects from ever becoming what they might have been by persuading them that they were what they are not. In this fashion too a French teacher turns out his pupil to be an infant prodigy, and for the rest of his life to be nothing whatsoever. The empire of Russia will aspire to conquer Europe, but will itself be conquered. The Tartars,² its subjects or neighbors, will become its masters and ours, by a revolution that I regard as inevitable.

In line 2, the word “sounds” most nearly means

Just as, before putting up a large building, the architect surveys and sounds the site to see if it will bear the weight, the wise legislator does not begin by laying down laws good in themselves, but by investigating the fitness of the people, for which they are destined, to receive them. Plato refused to legislate for the Arcadians and the Cyrenaeans,¹ because he knew that both peoples were rich and could not tolerate equality. Also, good laws and bad men were found together in Crete, because Minos had inflicted discipline on a people already burdened with vice.

A thousand nations that have achieved earthly greatness could never have endured good laws. Even those nations that could have endured good laws could have done so only for a very brief period of their long history. Most peoples, like most men, are docile only in youth. As they grow old they become incorrigible. Once customs have become established and prejudices inveterate, it is dangerous and useless to attempt their reformation. The people, like the foolish and cowardly patients who rave at sight of the doctor, can no longer bear that any one should lay hands on its faults to remedy them.

There are indeed times in the history of States when, just as some kinds of illness turn men’s heads and make them forget the past, periods of violence and revolution do to peoples what these crises do to individuals. Horror of the past takes the place of forgetfulness, and the state, set on fire by civil wars, is born again, so to speak, from its ashes, and takes on anew, fresh from the jaws of death, the vigor of youth. Such was Sparta at the time of Lycurgus.

But such events are rare exceptions, the cause of which is always to be found in the particular constitution of the state concerned. Such renewals cannot even happen twice to the same nation, for it can make itself free as long as it remains barbarous, but not when the civic impulse has lost its vigor. Then disturbances may destroy it, but revolutions cannot mend it: it needs a master, and not a liberator. Free peoples, be mindful of this maxim: “Liberty may be gained, but can never be recovered.”

There is for nations, as for men, a threshold of maturity before which they should not be made subject to laws. But the maturity of a people is not always easily recognizable, and, if it is anticipated, the work is spoiled. One people is amenable to discipline from the beginning: another, not after ten centuries. Russia will never be really civilized, because it was civilized too soon. Peter the Great had a genius for imitation, but he lacked true genius, which is creative and makes all from nothing. He did some good things, but most of what he did was out of place. He saw that his nation was barbarous, but did not see that it was not ripe for civilization: he wanted to civilize it when it needed only hardening. His first wish was to make Germans or Englishmen, when he ought to have been making Russians; and he prevented his subjects from ever becoming what they might have been by persuading them that they were what they are not. In this fashion too a French teacher turns out his pupil to be an infant prodigy, and for the rest of his life to be nothing whatsoever. The empire of Russia will aspire to conquer Europe, but will itself be conquered. The Tartars,² its subjects or neighbors, will become its masters and ours, by a revolution that I regard as inevitable.

In the first paragraph, the author discusses the activities of an architect in order to make the point that

Just as, before putting up a large building, the architect surveys and sounds the site to see if it will bear the weight, the wise legislator does not begin by laying down laws good in themselves, but by investigating the fitness of the people, for which they are destined, to receive them. Plato refused to legislate for the Arcadians and the Cyrenaeans,¹ because he knew that both peoples were rich and could not tolerate equality. Also, good laws and bad men were found together in Crete, because Minos had inflicted discipline on a people already burdened with vice.

A thousand nations that have achieved earthly greatness could never have endured good laws. Even those nations that could have endured good laws could have done so only for a very brief period of their long history. Most peoples, like most men, are docile only in youth. As they grow old they become incorrigible. Once customs have become established and prejudices inveterate, it is dangerous and useless to attempt their reformation. The people, like the foolish and cowardly patients who rave at sight of the doctor, can no longer bear that any one should lay hands on its faults to remedy them.

There are indeed times in the history of States when, just as some kinds of illness turn men’s heads and make them forget the past, periods of violence and revolution do to peoples what these crises do to individuals. Horror of the past takes the place of forgetfulness, and the state, set on fire by civil wars, is born again, so to speak, from its ashes, and takes on anew, fresh from the jaws of death, the vigor of youth. Such was Sparta at the time of Lycurgus.

But such events are rare exceptions, the cause of which is always to be found in the particular constitution of the state concerned. Such renewals cannot even happen twice to the same nation, for it can make itself free as long as it remains barbarous, but not when the civic impulse has lost its vigor. Then disturbances may destroy it, but revolutions cannot mend it: it needs a master, and not a liberator. Free peoples, be mindful of this maxim: “Liberty may be gained, but can never be recovered.”

There is for nations, as for men, a threshold of maturity before which they should not be made subject to laws. But the maturity of a people is not always easily recognizable, and, if it is anticipated, the work is spoiled. One people is amenable to discipline from the beginning: another, not after ten centuries. Russia will never be really civilized, because it was civilized too soon. Peter the Great had a genius for imitation, but he lacked true genius, which is creative and makes all from nothing. He did some good things, but most of what he did was out of place. He saw that his nation was barbarous, but did not see that it was not ripe for civilization: he wanted to civilize it when it needed only hardening. His first wish was to make Germans or Englishmen, when he ought to have been making Russians; and he prevented his subjects from ever becoming what they might have been by persuading them that they were what they are not. In this fashion too a French teacher turns out his pupil to be an infant prodigy, and for the rest of his life to be nothing whatsoever. The empire of Russia will aspire to conquer Europe, but will itself be conquered. The Tartars,² its subjects or neighbors, will become its masters and ours, by a revolution that I regard as inevitable.

The author suggests that long-established societies are characterized primarily by

Just as, before putting up a large building, the architect surveys and sounds the site to see if it will bear the weight, the wise legislator does not begin by laying down laws good in themselves, but by investigating the fitness of the people, for which they are destined, to receive them. Plato refused to legislate for the Arcadians and the Cyrenaeans,¹ because he knew that both peoples were rich and could not tolerate equality. Also, good laws and bad men were found together in Crete, because Minos had inflicted discipline on a people already burdened with vice.

A thousand nations that have achieved earthly greatness could never have endured good laws. Even those nations that could have endured good laws could have done so only for a very brief period of their long history. Most peoples, like most men, are docile only in youth. As they grow old they become incorrigible. Once customs have become established and prejudices inveterate, it is dangerous and useless to attempt their reformation. The people, like the foolish and cowardly patients who rave at sight of the doctor, can no longer bear that any one should lay hands on its faults to remedy them.

There are indeed times in the history of States when, just as some kinds of illness turn men’s heads and make them forget the past, periods of violence and revolution do to peoples what these crises do to individuals. Horror of the past takes the place of forgetfulness, and the state, set on fire by civil wars, is born again, so to speak, from its ashes, and takes on anew, fresh from the jaws of death, the vigor of youth. Such was Sparta at the time of Lycurgus.

But such events are rare exceptions, the cause of which is always to be found in the particular constitution of the state concerned. Such renewals cannot even happen twice to the same nation, for it can make itself free as long as it remains barbarous, but not when the civic impulse has lost its vigor. Then disturbances may destroy it, but revolutions cannot mend it: it needs a master, and not a liberator. Free peoples, be mindful of this maxim: “Liberty may be gained, but can never be recovered.”

There is for nations, as for men, a threshold of maturity before which they should not be made subject to laws. But the maturity of a people is not always easily recognizable, and, if it is anticipated, the work is spoiled. One people is amenable to discipline from the beginning: another, not after ten centuries. Russia will never be really civilized, because it was civilized too soon. Peter the Great had a genius for imitation, but he lacked true genius, which is creative and makes all from nothing. He did some good things, but most of what he did was out of place. He saw that his nation was barbarous, but did not see that it was not ripe for civilization: he wanted to civilize it when it needed only hardening. His first wish was to make Germans or Englishmen, when he ought to have been making Russians; and he prevented his subjects from ever becoming what they might have been by persuading them that they were what they are not. In this fashion too a French teacher turns out his pupil to be an infant prodigy, and for the rest of his life to be nothing whatsoever. The empire of Russia will aspire to conquer Europe, but will itself be conquered. The Tartars,² its subjects or neighbors, will become its masters and ours, by a revolution that I regard as inevitable.

 The author mentions “Sparta at the time of Lycurgus” primarily as an example of a place where

Just as, before putting up a large building, the architect surveys and sounds the site to see if it will bear the weight, the wise legislator does not begin by laying down laws good in themselves, but by investigating the fitness of the people, for which they are destined, to receive them. Plato refused to legislate for the Arcadians and the Cyrenaeans,¹ because he knew that both peoples were rich and could not tolerate equality. Also, good laws and bad men were found together in Crete, because Minos had inflicted discipline on a people already burdened with vice.

A thousand nations that have achieved earthly greatness could never have endured good laws. Even those nations that could have endured good laws could have done so only for a very brief period of their long history. Most peoples, like most men, are docile only in youth. As they grow old they become incorrigible. Once customs have become established and prejudices inveterate, it is dangerous and useless to attempt their reformation. The people, like the foolish and cowardly patients who rave at sight of the doctor, can no longer bear that any one should lay hands on its faults to remedy them.

There are indeed times in the history of States when, just as some kinds of illness turn men’s heads and make them forget the past, periods of violence and revolution do to peoples what these crises do to individuals. Horror of the past takes the place of forgetfulness, and the state, set on fire by civil wars, is born again, so to speak, from its ashes, and takes on anew, fresh from the jaws of death, the vigor of youth. Such was Sparta at the time of Lycurgus.

But such events are rare exceptions, the cause of which is always to be found in the particular constitution of the state concerned. Such renewals cannot even happen twice to the same nation, for it can make itself free as long as it remains barbarous, but not when the civic impulse has lost its vigor. Then disturbances may destroy it, but revolutions cannot mend it: it needs a master, and not a liberator. Free peoples, be mindful of this maxim: “Liberty may be gained, but can never be recovered.”

There is for nations, as for men, a threshold of maturity before which they should not be made subject to laws. But the maturity of a people is not always easily recognizable, and, if it is anticipated, the work is spoiled. One people is amenable to discipline from the beginning: another, not after ten centuries. Russia will never be really civilized, because it was civilized too soon. Peter the Great had a genius for imitation, but he lacked true genius, which is creative and makes all from nothing. He did some good things, but most of what he did was out of place. He saw that his nation was barbarous, but did not see that it was not ripe for civilization: he wanted to civilize it when it needed only hardening. His first wish was to make Germans or Englishmen, when he ought to have been making Russians; and he prevented his subjects from ever becoming what they might have been by persuading them that they were what they are not. In this fashion too a French teacher turns out his pupil to be an infant prodigy, and for the rest of his life to be nothing whatsoever. The empire of Russia will aspire to conquer Europe, but will itself be conquered. The Tartars,² its subjects or neighbors, will become its masters and ours, by a revolution that I regard as inevitable.

The phrase “particular constitution of the state” refers most specifically to

Just as, before putting up a large building, the architect surveys and sounds the site to see if it will bear the weight, the wise legislator does not begin by laying down laws good in themselves, but by investigating the fitness of the people, for which they are destined, to receive them. Plato refused to legislate for the Arcadians and the Cyrenaeans,¹ because he knew that both peoples were rich and could not tolerate equality. Also, good laws and bad men were found together in Crete, because Minos had inflicted discipline on a people already burdened with vice.

A thousand nations that have achieved earthly greatness could never have endured good laws. Even those nations that could have endured good laws could have done so only for a very brief period of their long history. Most peoples, like most men, are docile only in youth. As they grow old they become incorrigible. Once customs have become established and prejudices inveterate, it is dangerous and useless to attempt their reformation. The people, like the foolish and cowardly patients who rave at sight of the doctor, can no longer bear that any one should lay hands on its faults to remedy them.

There are indeed times in the history of States when, just as some kinds of illness turn men’s heads and make them forget the past, periods of violence and revolution do to peoples what these crises do to individuals. Horror of the past takes the place of forgetfulness, and the state, set on fire by civil wars, is born again, so to speak, from its ashes, and takes on anew, fresh from the jaws of death, the vigor of youth. Such was Sparta at the time of Lycurgus.

But such events are rare exceptions, the cause of which is always to be found in the particular constitution of the state concerned. Such renewals cannot even happen twice to the same nation, for it can make itself free as long as it remains barbarous, but not when the civic impulse has lost its vigor. Then disturbances may destroy it, but revolutions cannot mend it: it needs a master, and not a liberator. Free peoples, be mindful of this maxim: “Liberty may be gained, but can never be recovered.”

There is for nations, as for men, a threshold of maturity before which they should not be made subject to laws. But the maturity of a people is not always easily recognizable, and, if it is anticipated, the work is spoiled. One people is amenable to discipline from the beginning: another, not after ten centuries. Russia will never be really civilized, because it was civilized too soon. Peter the Great had a genius for imitation, but he lacked true genius, which is creative and makes all from nothing. He did some good things, but most of what he did was out of place. He saw that his nation was barbarous, but did not see that it was not ripe for civilization: he wanted to civilize it when it needed only hardening. His first wish was to make Germans or Englishmen, when he ought to have been making Russians; and he prevented his subjects from ever becoming what they might have been by persuading them that they were what they are not. In this fashion too a French teacher turns out his pupil to be an infant prodigy, and for the rest of his life to be nothing whatsoever. The empire of Russia will aspire to conquer Europe, but will itself be conquered. The Tartars,² its subjects or neighbors, will become its masters and ours, by a revolution that I regard as inevitable.

The author suggests that Peter the Great’s main flaw was