| GRE考试易错题（2017/8/31） |
| 第1题：从1,2,3,4,5,6,7,8,9中选出三个数字组成一个三位数,这个三位数的digits中有两个相同,另一个digit与其它两个都不同,问共有多少个这样的三位数?() A.72 B.144 C.180 D.216 E.54 |
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| 第2题：Aboxcontains100balls,numberedfrom1to100.Ifthreeballsareselectedatrandomandwithreplacementfromthebox,whatistheprobabilitythatthesumofthethreenumbersontheballsselectedfromtheboxwillbeodd?() A.1/4 B.3/8 C.1/2 D.5/8 E.3/4 |
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| 第3、4、5、6、7、8、9、10题：Many theories have been formulated to explain the role of grazers such as zooplankton in controlling the amount of planktonic algae (phytoplankton)in lakes. The first theories of such grazer control were merely based on observations of negative correlations between algal and zooplankton numbers. A low number of algal cells in the presence of a high number of grazers suggested, but did not prove, that the grazers had removed most of the algae. The converse observation, of the absence of grazers in areas of high phytoplankton concentration, led Hardy to propose his principle of animal exclusion, which hypothesized that phytoplankton produced a repellent that excluded grazers from regions of high phytoplankton concentration. This was the first suggestion of algal defenses against grazing. Perhaps the fact that many of these first studies considered only algae of a size that could be collected in a net (net phytoplankton), a practice that overlooked the smaller phytoplankton (nannoplankton)that we now know grazers are most likely to feed on, led to a de-emphasis of the role of grazers in subsequent research. Increasingly, as in the individual studies of Lund, Round, and Reynolds, researchers began to stress the importance of environmental factors such as temperature, light, and water movements in controlling algal numbers. These environmental factors were amenable to field monitoring and to simulation in the laboratory. Grazing was believed to have some effect on algal numbers, especially after phytoplankton growth rates declined at the end of bloom periods, but grazing was considered a minor component of models that predicted algal population dynamics. The potential magnitude of grazing pressure on freshwater phytoplankton has only recently been determined empirically. Studies by Hargrave and Geen estimated natural community grazing rates by measuring feeding rates of individual zooplankton species in the laboratory and then computing community grazing rates for field conditions using the known population density of grazers. The high estimates of grazing pressure postulated by these researchers were not fully accepted, however, until the grazing rates of zooplankton were determined directly in the field, by means of new experimental techniques. Using a specially prepared feeding chamber, Haney was able to record zooplankton grazing rates in natural field conditions. In the periods of peak zooplankton abundance, that is, in the late spring and in the summer, Haney recorded maximum daily community grazing rates, for nutrient-poor lakes and bog lakes, respectively, of 6.6 percent and 114 percent of daily phytoplankton production. Cladocerans had higher grazing rates than copepods, usually accounting for 80 percent of the community grazing rate. These rates varied seasonally, reaching the lowest point in the winter and early spring. Haney’s thorough research provides convincing field evidence that grazers can exert significant pressure on phytoplankton population. 20. The author most likely mentions Hardy’s principle of animal exclusion in order to (A)give an example of one theory about the interaction of grazers and phytoplankton (B)defend the first theory of algal defenses against grazing (C)support the contention that phytoplankton numbers are controlled primarily by environmental factors (D)demonstrate the superiority of laboratory studies of zooplankton feeding rates to other kinds of studies of such rates (E)refute researchers who believed that low numbers of phytoplankton indicated the grazing effect of low numbers of zooplankton 21. It can be inferred from the passage that the “first theories” of grazer control mentioned in line 4 would have been more convincing if researchers had been able to (A)observe high phytoplankton numbers under natural lake conditions (B)discover negative correlations between algae and zooplankton numbers from their field research (C)understand the central importance of environmental factors in controlling the growth rates of phytoplankton (D)make verifiable correlations of cause and effect between zooplankton and phytoplankton numbers (E)invent laboratory techniques that would have allowed them to bypass their field research concerning grazer control 22. Which of the following, if true, would call into question Hardy’s principle of animal exclusion? (A)Zooplankton are not the only organisms that are affected by phytoplankton repellents. (B)Zooplankton exclusion is unrelated to phytoplankton population density. (C)Zooplankton population density is higher during some parts of the year than during others. (D)Net phytoplankton are more likely to exclude zooplankton than are nannoplankton. (E)Phytoplankton numbers can be strongly affected by environmental factors. 23. The author would be likely to agree with which of the following statements regarding the pressure of grazers on phytoplankton numbers? I. Grazing pressure can vary according to the individual type of zooplankton. II. Grazing pressure can be lower in nutrient-poor lakes than in bog lakes. III. Grazing tends to exert about the same pressure as does temperature. (A)I only (B)III only (C)I and II only (D)II and III only (E)I, II, and III 24. The passage supplies information to indicate that Hargrave and Geen’s conclusion regarding the grazing pressure exerted by zooplankton on phytoplankton numbers was most similar to the conclusion regarding grazing pressure reached by which of the following researchers? (A)Hardy (B)Lund (C)Round (D)Reynolds (E)Haney 25. It can be inferred from the passage that one way in which many of the early researchers on grazer control could have improved their data would have been to (A)emphasize the effects of temperature, rather than of light, on phytoplankton (B)disregard nannoplankton in their analysis of phytoplankton numbers (C)collect phytoplankton of all sizes before analyzing the extent of phytoplankton concentration (D)recognize that phytoplankton other than net phytoplankton could be collected in a net (E)understand the crucial significance of net phytoplankton in the diet of zooplankton 26. According to the passage, Hargrave and Geen did which of the following in their experiments? (A)They compared the grazing rates of individual zooplankton species in the laboratory with the natural grazing rates of these species. (B)The hypothesized about the population density of grazers in natural habitats by using data concerning the population density of grazers in the laboratory. (C)They estimated the community grazing rates of zooplankton in the laboratory by using data concerning the natural community grazing rates of zooplankton. (D)They estimated the natural community grazing rates of zooplankton by using data concerning the known population density of phytoplankton. (E)They estimated the natural community grazing rates of zooplankton by using laboratory data concerning the grazing rates of individual zooplankton species. 27. Which of the following is a true statement about the zooplankton numbers and zooplankton grazing rates observed in Haney’s experiments? (A)While zooplankton numbers began to decline in August, zooplankton grazing rates began to increase. (B)Although zooplankton numbers were high in May, grazing rates did not become high until January. (C)Both zooplankton numbers and grazing rates were higher in December than in November. (D)Both zooplankton numbers and grazing rates were lower in March than in June. (E)Both zooplankton numbers and grazing rates were highest in February. |
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| 第11、12、13、14、15、16、17、18题： The historian Frederick J. Turner wrote in the 1890’s that the agrarian discontent that had been developing steadily in the United States since about 1870 had been precipitated by the closing of the internal frontier—that is, the depletion of available new land needed for further expansion of the American farming system. Not only was Turner’s thesis influential at the time, it was later adopted and elaborated by other scholars, such as John D. Hicks in The Populist Revolt (1931). Actually, however, new lands were taken up for farming in the United States throughout and beyond the nineteenth century. In the 1890’s, when agrarian discontent had become most acute, 1,100,000 new farms were settled, which was 500,000 more than had been settled during the previous decade. After 1890, under the terms of the Homestead Act and its successors, more new land was taken up for farming than had been taken up for this purpose in the United States up until that time. It is true that a high proportion of the newly farmed land was suitable only for grazing and dry farming, but agricultural practices had become sufficiently advanced to make it possible to increase the profitability of farming by utilizing even these relatively barren lands. The emphasis given by both scholars and statesmen to the presumed disappearance of the American frontier helped to obscure the great importance of changes in the conditions and consequences of international trade that occurred during the second half of the nineteenth century. In 1869 the Suez Canal was opened and the first transcontinental railroad in the United States was completed. An extensive network of telegraph and telephone communications was spun: Europe was connected by submarine cable with the United States in 1866 and with South America in 1874. By about 1870 improvements in agricultural technology made possible the full exploitation of areas that were most suitable for extensive farming on a mechanized basis. Huge tracts of land were being settled and farmed in Argentina, Australia, Canada, and in the American West, and these areas were joined with one another and with the countries of Europe into an interdependent market system. As a consequence, agrarian depressions no longer were local or national in scope, and they struck several nations whose internal frontiers had not vanished or were not about to vanish. Between the early 1870’s and the 1890’s, the mounting agrarian discontent in America paralleled the almost uninterrupted decline in the prices of American agricultural products on foreign markets. Those staple-growing farmers in the United States who exhibited the greatest discontent were those who had become most dependent on foreign markets for the sale of their products. Insofar as Americans had been deterred from taking up new land for farming, it was because market conditions had made this period a perilous time in which to do so. 20. The author is primarily concerned with (A)showing that a certain interpretation is better supported by the evidence than is an alternative explanation (B)developing an alternative interpretation by using sources of evidence that formerly had been unavailable (C)questioning the accuracy of the evidence that most scholars have used to counter the author’s own interpretation (D)reviewing the evidence that formerly had been thought to obscure a valid interpretation (E)presenting evidence in support of a controversial version of an earlier interpretation 21. According to the author, changes in the conditions of international trade resulted in an (A)underestimation of the amount of new land that was being famed in the United States (B)underutilization of relatively small but rich plots of land (C)overexpansion of the world transportation network for shipping agricultural products (D)extension of agrarian depressions beyond national boundaries (E)emphasis on the importance of market forces in determining the prices of agricultural products 22. The author implies that the change in the state of the American farmer’s morale during the latter part of the nineteenth century was traceable to the American farmer’s increasing perception that the (A)costs of cultivating the land were prohibitive within the United States (B)development of the first transcontinental railroad in the United States occurred at the expense of the American farmer (C)American farming system was about to run out of the new farmland that was required for its expansion (D)prices of American agricultural products were deteriorating especially rapidly on domestic markets (E)proceeds from the sales of American agricultural products on foreign markets were unsatisfactory 23. According to the passage, which of the following occurred prior to 1890? (A)Frederick J. Turner’s thesis regarding the American frontier became influential. (B)The Homestead Act led to an increase in the amount of newly farmed land in the United States. (C)The manufacturers of technologically advanced agricultural machinery rapidly increased their marketing efforts. (D)Direct lines of communication were constructed between the United States and South America. (E)Technological advances made it fruitful to farm extensively on a mechanized basis. 24. The author implies that, after certain territories and countries had been joined into an interdependent market system in the nineteenth century, agrarian depressions within that system (A)spread to several nations, excluding those in which the internal frontier remained open (B)manifested themselves in several nations, including those in which new land remained available for farming (C)slowed down the pace of new technological developments in international communications and transportation (D)affected the local and national prices of the nonagricultural products of several nations (E)encouraged several nations to sell more of their agricultural products on foreign markets 25. The author provides information concerning newly farmed lands in the United States (lines 11-27)as evidence in direct support of which of the following? (A)A proposal by Frederick J. Turner that was later disputed by John D. Hicks (B)An elaboration by John D. Hicks of a thesis that formerly had been questioned by Frederick J. Turner (C)The established view that was disputed by those scholars who adopted the thesis of Frederick J. Turner (D)The thesis that important changes occurred in the nature of international trade during the second half of the nineteenth century (E)The view that the American frontier did not become closed during the nineteenth century or soon thereafter 26. The author implies that the cause of the agrarian discontent was (A)masked by the vagueness of the official records on newly settled farms (B)overshadowed by disputes on the reliability of the existing historical evidence (C)misidentified as a result of influential but erroneous theorizing (D)overlooked because of a preoccupation with market conditions (E)undetected because visible indications of the cause occurred so gradually and sporadically 27. The author’s argument implies that, compared to the yearly price changes that actually occurred on foreign agricultural markets during the 1880’s, American farmers would have most preferred yearly price changes that were (A)much smaller and in the same direction (B)much smaller but in the opposite direction (C)slightly smaller and in the same direction (D)similar in size but in the opposite direction (E)slightly greater and in the same direction |
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| 第19题：TheprobabilityofAis60%andtheprobabilityofBis50%,whatisthemostpossibleprobabilitythatneitherAnorBwouldhappen?() A.0.80 B.0.40 C.0.75 D.0.55 E.0.68 |
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