GRE阅读练习每日一篇(二十七)

　　编辑点评： GRE阅读的方法相信大家已经积累了很多了，本文就为大家提供一些GRE阅读的材料，大家来练一练，把平时学到的东西运用到实际中，也多多积累词汇和句子，提高自己的阅读能力。

　　每天做一些标准的GRE阅读练习，有助于大家在GRE考试的复习过程中不断地进行练习和总结。希望大家在进行GRE阅读练习时，充分运用平时所积累的知识，这样才能有效果。

　　Whether the languages of the ancient American peoples were used for expressing abstract universal concepts can be clearly answered in the case of Nahuatl. Nahuatl, like Greek and German, is a language that allows the formation of extensive compounds. By the combination of radicals or semantic elements, single compound words can express complex conceptual relations, often of an abstract universal character.

　　The tlamatinime were able to use this rich stock of abstract terms to express the nuances of their thought. They also availed themselves of other forms of expression with metaphorical meaning, some probably original, some derived from Toltec coinages. Of these forms the most characteristic in Nahuatl is the juxtaposition of two words that, because they are synonyms, associated terms, or even contraries, complement each other to evoke one single idea. Used as metaphor, the juxtaposed terms connote specific or essential traits of the being they refer to, introducing a mode of poetry as an almost habitual form of expression.

　　17. A main purpose of the passage is to

　　delineate the function of the tlamatinime in Nahuatl society

　　explain the abstract philosophy of the Nahuatl thinkers

　　argue against a theory of poetic expression by citing evidence about the Nahuatl

　　explore the rich metaphorical heritage the Nahuatl received from the Toltecs

　　describe some conceptual and aesthetic resources of the Nahuatl language

　　18. According to the passage, some abstract universal ideas can be expressed in Nahuatl by

　　taking away from a word any reference to particular instances

　　removing a word from its associations with other words

　　giving a word a new and opposite meaning

　　putting various meaningful elements together in one word

　　turning each word of a phrase into a poetic metaphor

　　19. It can be inferred solely from the information in the passage that

　　there are many languages that, like Greek or German, allow extensive compounding

　　all abstract universal ideas are ideas of complex relations

　　some record or evidence of the thought of the tlamatinime exists

　　metaphors are always used in Nahuatl to express abstract conceptual relationships

　　the abstract terms of the Nahuatl language are habitually used in poetry

　　Many theories have been formulated to explain the role of grazers such as zooplankton in controlling the amount of planktonic algae 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 , a practice that overlooked the smaller phytoplankton 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

　　give an example of one theory about the interaction of grazers and phytoplankton

　　defend the first theory of algal defenses against grazing

　　support the contention that phytoplankton numbers are controlled primarily by environmental factors

　　demonstrate the superiority of laboratory studies of zooplankton feeding rates to other kinds of studies of such rates

　　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

　　observe high phytoplankton numbers under natural lake conditions

　　discover negative correlations between algae and zooplankton numbers from their field research

　　understand the central importance of environmental factors in controlling the growth rates of phytoplankton

　　make verifiable correlations of cause and effect between zooplankton and phytoplankton numbers

　　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?

　　Zooplankton are not the only organisms that are affected by phytoplankton repellents.

　　Zooplankton exclusion is unrelated to phytoplankton population density.

　　Zooplankton population density is higher during some parts of the year than during others.

　　Net phytoplankton are more likely to exclude zooplankton than are nannoplankton.

　　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.

　　I only

　　III only

　　I and II only

　　II and III only

　　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?

　　Hardy

　　Lund

　　Round

　　Reynolds

　　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

　　emphasize the effects of temperature, rather than of light, on phytoplankton

　　disregard nannoplankton in their analysis of phytoplankton numbers

　　collect phytoplankton of all sizes before analyzing the extent of phytoplankton concentration

　　recognize that phytoplankton other than net phytoplankton could be collected in a net

　　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?

　　They compared the grazing rates of individual zooplankton species in the laboratory with the natural grazing rates of these species.

　　The hypothesized about the population density of grazers in natural habitats by using data concerning the population density of grazers in the laboratory.

　　They estimated the community grazing rates of zooplankton in the laboratory by using data concerning the natural community grazing rates of zooplankton.

　　They estimated the natural community grazing rates of zooplankton by using data concerning the known population density of phytoplankton.

　　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?

　　While zooplankton numbers began to decline in August, zooplankton grazing rates began to increase.

　　Although zooplankton numbers were high in May, grazing rates did not become high until January.

　　Both zooplankton numbers and grazing rates were higher in December than in November.

　　Both zooplankton numbers and grazing rates were lower in March than in June.

　　Both zooplankton numbers and grazing rates were highest in February.

　　答案：17-27：EDCADBCECED