good point,and u got it; i was wondering that 2,

来源: yijuhua 于 2009-08-05 14:15:25 [] [博客] [旧帖] [给我悄悄话] 阅读数 : (150 bytes)
本帖于 2009-08-23 22:35:48 时间, 由普通用户 开心豆豆 编辑

this is why i did not have the answer, and did not know how to answer that question, actually myself.

it was in a toefl prepa book N years ago.

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