学英语语法情态动词+ have +过去分词

　　1) may(might) have + done sth, can (could) have + done sth　学英语语法这个句型一般表现过去，揣摩从前时间里可能发生的事件。

　　　　Philip may (might) have been hurt seriously in the car accident.
Philip can (could) have been hurt seriously in the car accident.

　　2)　must have +done sth，对从前时光里可能产生的事件的揣测，语气较强，存在"断定"，"谅必"的意思。
---Linda has gone to work, but her bicycle is still here.
---She must have gone by bus.

　　3) ought to have done sth, should have done sth
学英语语法注意它们的区别：本应该做某事，而事实上并不做。否定句表示"不该做某事而做了"。
You ought to (should) have been more careful in this experiment.
He ought not to have thrown the old clothes away.（事实上已扔了。）
ought to 在语气上比should 要强。

　　4) needn't have done sth　 本没必要做某事
I dressed very warmly for the trip, but I　needn't have done so. The weather was hot.

　　5) would like to have done sth　 本打算做某事　
学英语语法例句：I would like to have read the article, but I was very busy then.