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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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D：如果使用and it marks，则it和 an asteroid bigger than ... 并列，但此时it指代的对象是asteroid，而从句意看it应该指代an event。此外，此处的extinctions是特指某个extinction，所以应该用the。
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