【問題】PP破解版第43題

[chaosmaster]

43. 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

答案是D
但是不懂are為什麼會出現

[dibert8]

are 若省略,使得 but 可能和 survival 平衡
句意上 but 是主要結構,是 are not... but are... 的一部份; but 平衡兩個 be 動詞.

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