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74.   (28503-!-item-!-188;#058&003635)

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 or 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 reproduction or survival, but are

为什么选D不选C呢？D中but后的are和前面not后的名词the products of 不平行啊

are not ,but are 没什么问题啊

主要是和C相比 加上are的话 更能体现出在和前面的not 对应 因为中间插入了一个修饰语 C会造成歧义but对应because从句的部分 所以D更好

（D） but are simply random by-products of other evolutionary developments. 
                are 前面省略的是前句的主语biological traits
                

结构就是 biological traits are not ... , but are ...

我认为因为后面的句子接的是random adj. 所以要+ are 让句子对称。意思更明确

but会产生指向because还是主句的歧义