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GRE阅读模拟在线练习附答案二百八十一

2019-05-19 16:45:17来源：网络

　　对于GRE阅读部分，最好的练习资料就是模拟资料。通过模拟练习，可以让大家更好地发现自己在备考中的不足，重点攻克自己的短板内容，有效的提升阅读分数。下面新东方在线GRE频道为大家整理了详细的内容，供大家参考。

点击查看》》》【GRE阅读真题在线练习附答案汇总】

　　Since 1953, many experimental attem-pts tosynthesize the chemical consti-tuents of life under"primitive Earth condi-tions" have been performed, but none of the these experiments has producedanything approaching complexity of the simplestorganism. They have demonstrated, however, thata variety of the complex molecules currentlymaking up living organisms could have been presentin the early ocean and atmosphere, with only one limitation: such molecules are synthesizedfar less readily when oxygen-containing compounds dominate the atmosphere. Thereforesome scientists postulate that the Earth's earliest atmosphere, unlike that of today, wasdominated by hydrogen, methane, and ammonia.

　　From these studies, scientists have concluded that the surface of the primitive Earth wascovered 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 thatattempt to explain the development, from lager molecules, of the earliest self-duplicatingorganisms.

　　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

　　C.describe the development since 1953 of some scientists' understanding of how life began onEarth

　　D.demonstrate that the synthesis of life in the laboratory is too difficult for moderntechnology

　　E.describe how primitive atmospheric conditions produced the complex molecules ofliving organisms

　　It can be inferred from the passage that “some scientists” assume which of thefollowing 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 primitiveEarth conditions.

　　C.The presence of these molecules would necessarily precede the existence of simpleorganisms.

　　D.Experimental techniques will never be sufficiently sophisticated to produce in thelaboratory simple organisms from these chemical constituents.

　　E.Explanations could easily be developed to explain how simple molecules combined to formthese more complex ones.

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

　　A.enthusiasm

　　B.expectation

　　C.dismay

　　D.skepticism

　　E.antipathy

　　According to the passage, which of the following can be inferred about the process bywhich the chemical constituents of life were synthesized under primitive Earthconditions?

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

　　B.The synthesis is common in modern laboratories.

　　C.The synthesis occurs more readily in the atmosphere than in the ocean.

　　D.The synthesis easily produces the most complex organic molecules.

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

　　正确答案:C C D A

　　以上就是关于“GRE阅读模拟在线练习附答案二百八十一”的内容，更多精彩内容，请关注GRE频道!

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