gmatprep几道语法题，请帮忙

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1， With an awareness that there are connotations associated with the numbers 1 and 2 and the letters A and B,companies conducting consumer taste tests of foods or berverages typically choose numbers such as 697 or 483 to label the products.

A.With an awareness that there are connotations associated with the numbers 1 and 2 and the letters A and B
B.Because the numbers 1 and 2 and the letters A and B have connotaions they are aware of
C.Because of an awareness of the numbers 1 and 2 and the letters A and  B having connotations
D.Aware of the connotations of the numbers 1 and 2 and the letters A and B
E.Since the numbers 1 and 2 and the letters A and B have connotations associated with them and they are aware of it
 
答案是D, 请问aware of。。。。在句中到底做什么成分呀？

2. Paleontologist Stephen Jay Gould has argued that many biological traits are not the products of natural selection, favored due to their enhancement of reproduction or survival, but that they are simply random by-products of other evolutionary developments

A.due to their enhancement of reproduction or survival, but that they are
B.due to the reproduction of survival they enhance, but they are
C.because they enhance reproduction or survival, but
D.because they enhance reproduction or survival, but are
E.because of enhancing eaproduction or survival, but there are

答案D，我选了C 根据not。。。but，请问为什么but后还要补出are呢？这样不是不平行了？

3. The Nobel Prize in chemistry was awarded to three scientists for their discovery that plastic can be made electrically conductive-
    an advance that has led to improvments in film, television screens, and windows.

A. that plastic can be made electrically conductive- an advance that has led to
B. that plastic can be made electrically conductive- this advance leading
C. that plastic can be made to be electically conductive, and this advance led
D. of plastic's abillity to be made electrically conductive, with this advance leading
E. of plastic being able to be made electically coonductive - an advance that has led

答案是A, 我的问题是B为什么不行？

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只有自己顶一下，牛牛帮忙呀，快考了

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为啥没人理呀