Question

这两题有什么区别？

—She looks very happy. She ______ have passed the exam. [2007 江苏卷]
—I guess so. It’s not difficult after all.
. should B. could C. must D. might
—Where is my dictionary? I remember I put it here yesterday.
—You it in the wrong place. [2007 江西卷]
A.must put B.should have put C.might put D.might have put

Answer 1

第一题选C
第二题选D

追问

什么时候用might 什么时候用must？

追答

must have done
表示对过去某事的肯定猜测，译为：过去肯定做了某事。不存在 mustn't have done 的形式。其否定或疑问形式须用 can(could) 来表示. 例如：
Since the road is wet, it must have rained last night. 既然路是湿的，那昨天晚上肯定下雨了。
He can't have missed the way. I drew him a map. 他不可能迷路。我（当时）给他画了张图。
“The dictionary has disappeared. Who could have taken it?” 词典不见了，（过去）谁可能把它拿走了？
may / might have done
may / might have done 表示“过去可能做了某事”。may 比 might 表示的可能性在说话人看来稍大些。may/might not have done表示“过去可能没有做某事。”例如：
I can't find my keys. I may / might have left them at the school yesterday. 我找不到我的钥匙了。我可能昨天把他们落在学校了。
John may/might not have passed the exam; he looks very sad.约翰可能没有通过考试。他看起来很忧伤。
注意：may/might have done表推测不能用于疑问句中。

第一题从对话中的情景看，应当属于肯定推测，望采纳！