情态动词后接完成式
■表示对过去情况的推测
1. must have +P. P. 一定已经
2. can/could have + P. P. 可能已经
3. may/might have + P. P. 或许已经
用例：
He mu st have taken the book since it isn’t here. 他一定是把书拿走了,因为书已不在这里了。
What could have become of him now? 现在他可能怎么样了呢?
You may h ave noted that my address has changed. 你也许已经注意到我的地址变了。
She might have gone to have her hair waved. 她可能去烫发去了。
注意：could have done还 可表示“简直就要”。如：
I could have died laughing. 我简直要笑死了。
■表示轻微的责备或后悔
1. ought to /should + hav e + P. P. 本来应该做某 事(而实际上没做)
2. ought not to /shouldn’t + have + P. P. 本来不应该做某事( 而实际上却做了)
