对prep2-69 的疑惑
69. (28208-!-item-!-188;#058&003886)
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.
(A) which, causing plant and animal extinctions, marks (B) which caused the plant and animal extinctions marking (C) and causing plant and animal extinctions that mark (D) an event that caused plant and animal extinctions, and it marks (E) an event that caused the plant and animal extinctions that mark
key：E 答案E中 mark的时态为什么是一般现在时呢？
[此贴子已经被作者于2008-10-8 19:58:45编辑过] | 
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发表于 2008-10-8 19:58:00
