(2) may have done, might have done, could have done "___________________________"，就语气而言 could have done 所表的可能性更小些。

He may / might / could have left by nine. 他可能于九点前已离去。

(3) should have done / ought to have done 表示"____________________"但实际未做。

I should / ought to have left London before nine but I didn't.

(4) shouldn't have done / oughtn't to have done 表示"_____________"，但实际上又做了。

He shouldn't / oughtn't to have left London before nine but he did.

(5) can't / couldn't have done 表否定推测，"_____________"。

She can't / couldn't have gone to bed, for the light in her room is still on.

(6)could have done 可表示客观上"____________________"。 表示遗憾 He could have finished the work in time but he didn't work hard.

(7) I needn't have gone to the office yesterday (but I went there).

(8) might have done 还可表示过去"本可能发生但实际上没有发生的动作"。用于表示说话人对已发生事提出批评或意见。He might have given more help, even if he was very busy.

Ⅲ.高考例析

1. Sorry I'm late. I ________ have turned off the alarm clock and gone back to sleep again.

A. might 　　　　B. should 　　　　　C. can 　　　　　　D. will

2. I was really anxious about you. You_________ home without a word. （01 全国）

A. mustn't leave B. shouldn't have left C. couldn't have left D. needn't leave

3. - I'll tell Mary about her new job tomorrow.

- You________ her last week. （04 福建）

A．ought to tell B．would have told C．must tell D．should have told

- Oh, he ______ have been a very smart boy then. （04 全国IV）

5. He _______ have completed his work; otherwise, he wouldn't be enjoying himself by the

seaside. A. should B. must C. wouldn't D. can't

6. - Do you know where David is? I couldn't find him anywhere.

- Well. He have gone far-his coat's still here. （05湖北卷）

7. - The woman biologist stayed in Africa studying wild animals for 13 years before she returned. - Oh, dear! She _______ a lot of difficulties! (05 江苏卷)

A. may go through B. might go through

C. ought to have gone through D. must have gone through

8. I have lost one of my gloves. I ________ it somewhere. （05 北京春季）

A. must drop B. must have dropped

C. must be dropping D. must have been dropped

9. Mr. White _____ at 8:30 for the meeting, but he didn't show up.