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历年GRE习题（三）

时间：2011/7/8

　　SECTION A

　　As Gilbert White, Darwin, and others observed long ago, all species appear to have the innate capacity to increase their numbers from generation to generation. The task for ecologists is to untangle the environmental and biological factors that hold this intrinsic capacity for population growth in check over the long run. The great variety of dynamic behaviors exhibited by different populations makes this task more difficult: some populations remain roughly constant from year to year (from year to year: adv.年年); others exhibit regular cycles of abundance and scarcity; still others vary wildly, with outbreaks and crashes that are in some cases plainly correlated with the weather, and in other cases not.

　　To impose some order on this kaleidoscope of patterns, one school of thought proposes dividing populations into two groups. These ecologists posit that the relatively steady populations have “density-dependent” growth parameters; that is, rates of birth, death, and migration which depend strongly on population density. The highly varying populations have “density-independent” growth parameters, with vital rates buffeted by environmental events; these rates fluctuate in a way that is wholly independent of population density.

　　This dichotomy has its uses, but it can cause problems if taken too literally. For one thing, no population can be driven entirely by density-independent factors all the time. No matter how severely or unpredictably birth, death and migration rates may be fluctuating around their long-term averages, if there were no density-dependent effects, the population would, in the long run, either increase or decrease without bound (barring a miracle by which gains and losses canceled exactly). Put another way, it may be that on average 99 percent of all deaths in a population arise from density-independent causes, and only one percent from factors varying with density. The factors making up the one percent may seem unimportant, and their cause may be correspondingly hard to determine. Yet, whether recognized or not, they will usually determine the long-term average population density.

　　In order to understand the nature of the ecologist’s investigation, we may think of the density-dependent effects on growth parameters as the “signal” ecologists are trying to isolate and interpret, one that tends to make the population increase from relatively low values or decrease from relatively high ones, while the density-independent effects act to produce “noise” in the population dynamics (population dynamics: 种群动态;人口动态). For populations that remain relatively constant, or that oscillate around repeated cycles, the signal can be fairly easily characterized and its effects described, even though the causative biological mechanism may remain unknown. For irregularly fluctuating populations, we are likely to have too few observations to have any hope of extracting the signal from the overwhelming noise. But it now seems clear that all populations are regulated by a mixture of density-dependent and density-independent effects in varying proportions.

　　17. The author of the passage is primarily concerned with

　　(A) discussing two categories of factors that control population growth and assessing their relative importance

　　(B) describing how growth rates in natural populations fluctuate over time and explaining why these changes occur

　　(D) posing a fundamental question about environmental factors in population growth and presenting some currently accepted answers(A)

　　(E) refuting a commonly accepted theory about population density and offering a new alternative

　　18. It can be inferred from the passage that the author considers the dichotomy discussed in the second paragraph to be

　　(A) applicable only to erratically fluctuating populations

　　(B) useful, but only if its limitations are recognized

　　(D) a complete and sufficient way to account for observed phenomena(B)

　　(E) conceptually valid, but too confusing to apply on a practical basis

　　19. Which of the following statements can be inferred from the last paragraph?

　　(A) For irregularly fluctuating populations, doubling the number of observations made will probably result in the isolation of density-dependent effects.

　　(B) Density-dependent effects on population dynamics do not occur as frequently as do density-independent effects.

　　(C) At present, ecologists do not understand any of the underlying causes of the density-dependent effects they observe in population dynamics.

　　(D) Density-dependent effects on growth parameters are thought to be caused by some sort of biochemical “signaling” that ecologists hope eventually to understand.(E)

　　(E) It is sometimes possible to infer the existence of a density-dependent factor controlling population growth without understanding its causative mechanism.

　　20. According to the passage, which of the following is a true statement about density-dependent factors in population growth?

　　(A) They ultimately account for long-term population levels.

　　(B) They have little to do with long-term population dynamics.

　　(D) They include random environmental events.(A)

　　(E) They contradict current ecological assumptions about population dynamics.

　　21. According to the passage, all of the following behaviors have been exhibited by different populations EXCEPT:

　　(A) roughly constant population levels from year to year

　　(B) regular cycles of increases and decreases in numbers

　　(D) unchecked increases in numbers over many generations(D)

　　(E) sudden declines in numbers from time to time

　　22. The discussion concerning population in lines 24-40 serves primarily to

　　(A) demonstrate the difficulties ecologists face in studying density-dependent factors limiting population growth

　　(B) advocate more rigorous study of density-dependent factors in population growth

　　(D) give an example of how death rates function to limit population densities in typical populations(E)

　　(E) underline the importance of even small density-dependent factors in regulating long-term population densities

　　23. In the passage, the author does all of the following EXCEPT:

　　(A) cite the views of other biologists

　　(B) define a basic problem that the passage addresses

　　(D) describe the results of a particular study(D)

　　(E) draw a conclusion

　　In Raisin in the Sun, Lorraine Hansberry does not reject integration or the economic and moral promise of the American dream; rather, she remains loyal to this dream while looking, realistically, at its incomplete realization. Once we recognize this dual vision, we can accept the play’s ironic nuances as deliberate social commentaries by Hansberry rather than as the “unintentional” irony that Bigsby attributes to the work. Indeed a curiously persistent refusal to credit Hansberry with a capacity for intentional irony has led some critics to interpret the play’s thematic conflicts as mere confusion, contradiction, or eclecticism. Isaacs, for example, cannot easily reconcile Hansberry’s intense concern for her race with her ideal of human reconciliation. But the play’s complex view of Black self-esteem and human solidarity as compatible is no more “contradictory” than Du Bois’ famous, well-considered ideal of ethnic self-awareness coexisting with human unity, or Fanon’s emphasis on an ideal internationalism that also accommodates national identities and roles.

　　24. The author’s primary purpose in this passage is to

　　(A) explain some critics’ refusal to consider Raisin in the Sun a deliberately ironic play

　　(B) suggest that ironic nuances ally Raisin in the Sun with Du Bois’ and Fanon’s writings

　　(D) justify the inclusion of contradictory elements in Raisin in the Sun(E)

　　(E) affirm the thematic coherence underlying Raisin in the Sun

　　25. It can be inferred from the passage that the author believes which of the following about Hansberry’s use of irony in Raisin in the Sun?

　　(A) It derives from Hansberry’s eclectic approach to dramatic structure.

　　(B) It is justified by Hansberry’s loyalty to a favorable depiction of American life.

　　(D) It is more consistent with Hansberry’s concern for Black Americans than with her ideal of human reconciliation.(E)

　　(E) It reflects Hansberry’s reservations about the extent to which the American dream has been realized.

　　26. In which of the following does the author of the passage reinforce his criticism of responses such as Isaacs’ to Raisin in the Sun?

　　(A) The statement that Hansberry is “loyal” (line 3) to the American dream

　　(B) The description of Hansberry’s concern for Black Americans as “intense” (line 13)

　　(D) The description of Du Bois’ ideal as “well-considered” (line 17)(D)

　　(E) The description of Fanon’s internationalism as “ideal” (line 19)

　　27. The author of the passage would probably consider which of the following judgments to be most similar to the reasoning of critics described in lines 8-12?

　　(A) The world is certainly flat; therefore, the person proposing to sail around it is unquestionably foolhardy.

　　(B) Radioactivity cannot be directly perceived; therefore, a scientist could not possibly control it in a laboratory.

　　(D) Traditional social mores are beneficial to culture; therefore, anyone who deviates from them acts destructively.(C)

　　(E) Filmmakers who produce documentaries deal exclusively with facts; therefore, a filmmaker who reinterprets particular events is misleading us.

　　SECTION B

　　Some recent historians have argued that life in the British colonies in America from approximately 1763 to 1789 was marked by internal conflicts among colonists. Inheritors of some of the viewpoints of early twentieth-century Progressive historians such as Beard and Becker, these recent historians have put forward arguments that deserve evaluation.

　　The kind of conflict most emphasized by these historians is class conflict. Yet with the Revolutionary War dominating these years, how does one distinguish class conflict within that larger conflict? Certainly not by the side a person supported. Although many of these historians have accepted the earlier assumption that Loyalists represented an upper class, new evidence indicates that Loyalists, like rebels, were drawn from all socioeconomic classes. (It is nonetheless probably true that a larger percentage of the well-to-do joined the Loyalists than joined the rebels.) Looking at the rebel side, we find little evidence for the contention that lower-class rebels were in conflict with upper-class rebels. Indeed, the war effort against Britain tended to suppress class conflicts. Where it did not, the disputing rebels of one or another class usually became Loyalists. Loyalism thus operated as a safety valve to remove socioeconomic discontent that existed among the rebels. Disputes occurred, of course, among those who remained on the rebel side, but the extraordinary social mobility of eighteenth-century American society (with the obvious exception of slaves) usually prevented such disputes from hardening along class lines. Social structure was in fact so fluid—though recent statistics suggest a narrowing of economic opportunity as the latter half of the century progressed—that to talk about social classes at all requires the use of loose economic categories such as rich, poor, and middle class, or eighteenth-century designations like “the better sort.” Despite these vague categories, one should not claim unequivocally that hostility between recognizable classes cannot be legitimately observed. Outside of New York, however, there were very few instances of openly expressed class antagonism.

　　Having said this, however, one must add that there is much evidence to support the further claim of recent historians that sectional conflicts were common between 1763 and 1789. The “Paxton Boys” incident and the Regulator movement are representative examples of the widespread, and justified, discontent of western settlers against colonial or state governments dominated by eastern interests. Although undertones of class conflict existed beneath such hostility, the opposition was primarily geographical. Sectional conflict—which also existed between North and South—deserves further investigation.

　　In summary, historians must be careful about the kind of conflict they emphasize in eighteenth-century America. Yet those who stress the achievement of a general consensus among the colonists cannot fully understand that consensus without understanding the conflicts that had to be overcome or repressed in order to reach it.

　　17. The author considers the contentions made by the recent historians discussed in the passage to be

　　(A) potentially verifiable

　　(B) partially justified

　　(D) ingenious but flawed(B)

　　(E) capricious and unsupported

　　18. The author most likely refers to “historians such as Beard and Becker” (lines 5-6) in order to

　　(A) isolate the two historians whose work is most representative of the viewpoints of Progressive historians

　　(B) emphasize the need to find connections between recent historical writing and the work of earlier historians

　　(C) make a case for the importance of the views of the Progressive historians concerning eighteenth-century American life

　　(D) suggest that Progressive historians were the first to discover the particular internal conflicts in eighteenth-century American life mentioned in the passage(E)

　　(E) point out historians whose views of history anticipated some of the views of the recent historians mentioned in the passage

　　19. According to the passage, Loyalism during the American Revolutionary War served the function of

　　(A) eliminating the disputes that existed among those colonists who supported the rebel cause

　　(B) drawing upper, as opposed to lower, socioeconomic classes away from the rebel cause

　　(D) channeling conflict that existed within a socioeconomic class into the war effort against the rebel cause(E)

　　(E) absorbing members of socioeconomic groups on the rebel side who felt themselves in contention with members of other socioeconomic groups

　　20. The passage suggests that the author would be likely to agree with which of the following statements about the social structure of eighteenth-century American society?

　　I. It allowed greater economic opportunity than it did social mobility.

　　II. It permitted greater economic opportunity prior to 1750 than after 1750.

　　III. It did not contain rigidly defined socioeconomic divisions.

　　IV. It prevented economic disputes from arising among members of the society.

　　(A) I and IV only

　　(B) II and III only

　　(D) I, II, and III only(B)

　　(E) I, II, III, and IV

　　21. It can be inferred from the passage that the author would be most likely to agree with which of the following statements regarding socioeconomic class and support for the rebel and Loyalist causes during the American Revolutionary War?

　　(A) Identifying a person’s socioeconomic class is the least accurate method of ascertaining which side that person supported.

　　(B) Identifying a person as a member of the rebel or of the Loyalist side does not necessarily reveal that person’s particular socioeconomic class.

　　(C) Both the rebel and the Loyalist sides contained members of all socioeconomic classes, although there were fewer disputes among socioeconomic classes on the Loyalist side.

　　(D) Both the rebel and the Loyalist sides contained members of all socioeconomic classes, although the Loyalist side was made up primarily of members of the upper classes.(B)

　　(E) Both the rebel and the Loyalist sides contained members of all socioeconomic classes, although many upper-class rebels eventually joined the Loyalists.

　　22. The author suggests which of the following about the representativeness of colonial or state governments in America from 1763 to 1789?

　　(A) The governments inadequately represented the interests of people in western regions.

　　(B) The governments more often represented class interests than sectional interests.

　　(D) The governments were dominated by the interests of people of an upper socioeconomic class.(A)

　　(E) The governments of the northern colonies were less representative than were the governments of the southern colonies.

　　23. According to the passage, which of the following is a true statement about sectional conflicts in America between 1763 and 1789?

　　(A) These conflicts were instigated by eastern interests against western settlers.

　　(B) These conflicts were the most serious kind of conflict in America.

　　(D) These conflicts contained an element of class hostility.(D)

　　(E) These conflicts were motivated by class conflicts.

　　Since 1953, many experimental attempts to synthesize the chemical constituents of life under “primitive Earth conditions” have been performed, but none of these experiments has produced anything approaching the complexity of the simplest organism. They have demonstrated, however, that a variety of (a variety of: adj.多种的) the complex molecules currently making up living organisms could have been present in the early ocean and atmosphere, with only one limitation: such molecules are synthesized far less readily when oxygen-containing compounds dominate the atmosphere. Therefore some scientists postulate (to assume or claim as true, existent, or necessary: depend upon or start from the postulate of) that the Earth’s earliest atmosphere, unlike that of today, was dominated by hydrogen, methane, and ammonia.

　　From these studies, scientists have concluded that the surface of the primitive Earth was covered with oceans containing the molecules fundamental to life. Although, at present, scientists cannot explain how these relatively small molecules combined to produce larger, more complex molecules, some scientists have precipitously ventured hypotheses that attempt to explain the development, from lager molecules, of the earliest self-duplicating organisms.

　　24. According to the passage, which of the following can be inferred about the process by which the chemical constituents of life were synthesized under primitive Earth conditions?

　　(A) The synthesis is unlikely to occur under current atmospheric conditions.

　　(B) The synthesis is common in modern laboratories.

　　(D) The synthesis easily produces the most complex organic molecules.(A)

　　(E) The synthesis is accelerated by the presence of oxygen-containing compounds.

　　25. The primary purpose of the passage is to

　　(A) point out that theories about how life developed on Earth have changed little since 1953

　　(B) warn of increasing levels of hydrogen, methane, and ammonia in the Earth’s atmosphere

　　(D) demonstrate that the synthesis of life in the laboratory is too difficult for modern technology(C)

　　(E) describe how primitive atmospheric conditions produced the complex molecules of living organisms

　　26. It can be inferred from the passage that “some scientists” assume which of the following concerning “larger, more complex molecules” (line 20)?

　　(A) The earliest atmosphere was formed primarily of these molecules.

　　(B) Chemical processes involving these molecules proceeded much more slowly under primitive Earth conditions.

　　(D) Experimental techniques will never be sufficiently sophisticated to produce in the laboratory simple organisms from these chemical constituents.(C)

　　(E) Explanations could easily be developed to explain how simple molecules combined to form these more complex ones.

　　27. The author’s reaction to the attempts that have been made to explain the development of the first self-duplication organisms can best be described as one of

　　(A) enthusiasm

　　(B) expectation

　　(D) skepticism(D)

　　(E) antipathy