Question

You____Tom at the party yesterday;he went abroad for a holiday last week.

1. A.
   should have seen
2. B.
   might have seen
3. C.
   mustn’t have seen
4. D.
   couldn’t have seen

Answer 1

D
试题分析：句意：你昨天可能没有见到汤姆，他上周就去国外度假去了。（1）、“must + have + 过去分词”表示对过去发生的事情或状态进行推测，语气比较坚定，通常只用于肯定句。如：
It must have rained last night, for the ground is wet. 
You must have been mad to speak to the servant. 
（2）、“can / could + have + 过去分词”表示对过去某种情况的怀疑或不确定。can和could一般用于否定句和疑问句，could的语气较can弱。如：
I didn't see her at the meeting this morning; she can't / couldn't have spoken at the meeting.
He can't have finished the work so soon. 
（3）、“may / might + have + 过去分词”表示对已发生的动作或存在的状态进行不肯定的推测，might的语气比may弱一点。这种结构主要用于肯定句和否定句，疑问句改用can或could。如：
They may not have known it beforehand.
You might have read about it in the papers.
（4）、“should / ought to + have + 过去分词”表示过去本该做某事但没做，其否定式表示过去不该做某事但做了，这种句式含有不满或责备之意，ought to的语气比should强一些。如：
You ought to / should have studied harder. 你本应该更努力学习的。（但没有）
He oughtn't to / shouldn't have done that. 他本来就不该做那件事。（可是做了）
考点：考查情态动词+have done的用法
点评：情态动词+have done是高中阶段必须掌握的内容，是考生容易混淆的地方，也是考生容易失分的难点，考生应注意这方面的练习。
即学即练：Look at the time! We ______at the theatre ten minutes ago.
A.should have been    B.might have been  C.mustn’t have been D.couldn’t have been
解析：A  句意：瞧都什么时候了! 十分钟前我们就该到戏院了。