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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：这里which指代asteroid，然后提出主干就变成asteroid marks the end of era, 而在这里mark 这个end of era的不是小行星本身， 而是小行星撞击导致物种毁灭，杀掉
B： 这里『marking the end of the geologic era』如果是状语修饰cause，整句话应该示行星撞击这个事mark了一个end of era， 而不是行星cause了物种灭绝；如果作为后置定语那就是修饰extinctions, mark被放到了一个更弱的位置，更加不对。另外which指代的asteroid本身也不是发出cause行为的主体，错。
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