问题描述：
have seen 和seen的差别是什么?（急!）
— He can't find his hat.Have you seen it?— Yes,of course.I _____ it on his bed just now.[ ] A.saw B.have seen C.had seen D.to see
— He can't find his hat.Have you seen it?— Yes,of course.I _____ it on his bed just now.[ ] A.saw B.have seen C.had seen D.to see
问题解答：
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