攻破2017新gre逻辑阅读 每日一练15.

　　2011新gre考试实施以来，参加了新版gre考试的考生都觉得阅读部分的题难度增加了，这主要是由于新gre考试逻辑阅读需要考生的逻辑反应一定要比以前更快，可能考生还是有点不习惯，或是没有准备充足。那么，接下来的几天，小编将给大家搜索整理一些新gre考试逻辑阅读的练习题，希望考生能从平日的练习中总结规律，找到解题技巧。

　　Flatfish, such as the flounder, are among the few

　　vertebrates that lack approximate bilateral symmetry

　　(symmetry in which structures to the lt and right of the

　　body‘s midline are mirror images). Most striking among

　　5 the many asymmetries evident in an adult flatfish is eye

　　placement: bore maturity one eye migrates, so that in

　　an adult flatfish both eyes are on the same side of the head.

　　While in most species with asymmetries virtually

　　all adults share the same asymmetry, members of the

　　10 starry flounder species can be either lt-eyed

　　(both eyes on the lt side of head) or right-eyed.

　　In the waters between the United States and Japan,

　　the starry flounder populations vary from about 50 percent

　　lt-eyed off the United States West Coast, through about 70 percent

　　15 lt-eyed halfway between the United States and Japan, to

　　nearly 100 percent lt-eyed off the Japanese coast.获得更多gre考试咨询点击进入>>>>澳际免费咨询顾问或联系QQ客服：

　　Biologists call this kind of gradual variation over a certain

　　geographic rang a “cline" and interpret clines as strong

　　indications that the variation is adaptive, a

　　20 response to environmental differences. For the

　　starry flounder this interpretation implies that a

　　geometric difference (between fish that are mirror

　　images of one another) is adaptive, that lt-eyedness

　　in the Japanese starry flounder has been selected for, which provokes a

　　25 perplexing questions: what is the selective advantage in

　　having both eyes on one side rather than on the other?

　　The ease with which a fish can reverse the fect of the sidedness

　　of its eye asymmetry simply by turning

　　around has caused biologists to study internal anatomy,

　　30 especially the optic nerves, for the answer. In all flatfish

　　the optic nerves cross, so that the right optic nerve is joined

　　to the brain‘s lt side and vice versa. This crossing introduces

　　an asymmetry, as one optic nerve must

　　cross above or below the other. G. H. Parker

　　35 reasoned that if, for example, a flatfish‘s lt eye

　　migrated when the right optic nerve was on top, there

　　would be a twisting of nerves, which might be

　　mechanically disadvantageous. For starry flounders,

　　then, the lt-eyed variety would be selected against, since in a

　　40 starry flounder the lt optic nerve is uppermost.

　　The problem with the above explanation is that the

　　Japanese starry flounder population is almost exclusively

　　lt-eyed, and natural selection never promotes a purely

　　less advantageous variation. As other explanations

　　45 proved equally untenable, biologists concluded that

　　there is no important adaptive difference between

　　lt- eyedness and right-eyedness, and that the

　　two characteristics are genetically associated with some

　　other adaptively significant characteristic. This

　　50 situation is one commonly encountered by

　　evolutionary biologists, who must often decide

　　whether a characteristic is adaptive or selectively neutral.

　　As for the lt-eyed and right-eyed flatfish,

　　their difference, however striking, appears to be an

　　55 evolutionary red herring.

　　(456 words)

　　10. According to the passage, starry flounder differ from most other species of flatfish in that starry flounder

　　(A) are not basically bilaterally symmetric

　　(B) do not become asymmetric until adulthood

　　(C) do not all share the same asymmetry

　　(D) have both eyes on the same side of the head

　　(E) tend to cluster in only certain geographic regions For the following question, consider each of the choices separately and select all that apply

　　11. The author would be most likely to agree with which of the following statements about lt-eyedness and right-eyedness in the starry flounder?

　　□A They are adaptive variations by the starry flounder to environmental differences.

　　□B They do not seem to give obvious selective advantages to the starry flounder.

　　□C They occur in different proportions in different locations.

　　12. According to the passage, a possible disadvantage associated with eye migration in flatfish is that the optic nerves can

　　(A) adhere to one another

　　(B) detach from the eyes

　　(C) cross

　　(D) stretch

　　(E) twist

　　13. Which of the following best describes the organization of the passage as a whole?

　　(A) A phenomenon is described and an interpretation presented and rejected.

　　(B) A generalization is made and supporting evidence is supplied and weighed.

　　(C) A contradiction is noted and a resolution is suggested and then modified.

　　(D) A series of observations is presented and explained in terms of the dominant theory.

　　(E) A hypothesis is introduced and corroborated in the light of new evidence.

答案：C/BC/E/A

　　以上即是阅读练习题，对于新gre考试逻辑阅读，考生除了采取题海战术，其实更应该做的就是总结。如果能从平日的练习中找到解新gre考试逻辑阅读题的思路，那么，要比采取题海战术更好。

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