1) may(might) have + done sth， can (could) have + done sth表示過(guò)去，推測(cè)過(guò)去時(shí)間里可能發(fā)生的事情。例如：

Philip may (might) have been hurt seriously in the car accident. 菲力浦可能在車(chē)禍中受了重傷。

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

2) must have +done sth，對(duì)過(guò)去時(shí)間里可能發(fā)生的事情的推測(cè)，語(yǔ)氣較強(qiáng)，具有"肯定"，"諒必"的意思。例如：

——Linda has gone to work， but her bicycle is still here. 琳達(dá)已經(jīng)去上班了，但她的單車(chē)還在這兒。

——She must have gone by bus.肯定乘巴士去的。

3) ought to have done sth， should have done sth表示本應(yīng)該做某事，而事實(shí)上并沒(méi)有做。否定句表示"不該做某事而做了".例如：

You ought to (should) have been more careful in this experiment. 你當(dāng)時(shí)在做試驗(yàn)時(shí)應(yīng)該更仔細(xì)點(diǎn)。

He ought not to have thrown the old clothes away.他不該把舊衣服扔了。(事實(shí)上已扔了。)

ought to 在語(yǔ)氣上比should 要強(qiáng)。

4) needn’t have done sth表示本沒(méi)必要做某事，但做了。例如：

I dressed very warmly for the trip， but I needn’t have done so. The weather was hot.

旅行時(shí)，我衣服穿得較多，其實(shí)沒(méi)有必要。那時(shí)天很熱。

5) would like to have done sth表示本打算做某事，但沒(méi)做。例如：

I would like to have read the article， but I was very busy then. 我想讀這篇文章，但太忙了一直沒(méi)讀。