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题库 / Prep2007E2-SC-69
Sixty-five million years ago, according to some scientists, an asteroid bigger than Mount Everest slammed into North America, which, causing plant and animal extinctions, marks the end of the geologic era known as the Cretaceous Period.
which, causing plant and animal extinctions, marks
which caused the plant and animal extinctions marking
and causing plant and animal extinctions that mark
an event that caused plant and animal extinctions, and it marks
an event that caused the plant and animal extinctions that mark
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A选项：”which“ is ambiguous; therefore marks is unclear to mean the Cretaceous Period
B选项：”which“ is ambiguous;and marks并不能表示the plant and animal extinctions是the end of the geologic era known as the Cretaceous Period的重要标志；
C选项：and +现在分词，而不是动词，不符合平行原则，同时and后面的成分不能构成完整的句子，只是句子的组成部分；
D选项：which指代extinctions, 所以后面的marks应该是复数动词形式，即动词原形
E选项：tha指代extinctions, mark修饰extinctions.
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