should、would、could、need加have done時(shí)，肯定形式下的意思，都是情態(tài)動(dòng)詞的本意，加上還沒做的事；否定形式下的意思，都是情態(tài)動(dòng)詞的本意，加上已經(jīng)做了的事。

情態(tài)動(dòng)詞+have+done

一、“must+have+done”表示對(duì)過去事情的肯定推測(cè),譯成“一定做過某事”,該結(jié)構(gòu)只用于肯定句.

You must have been mad to speak to theservant.你和仆人說話,一定是發(fā)瘋了.

二、“can't+have+done”表示對(duì)過去事情的否定推測(cè),譯成“不可能做過某事”.

Mary can't have stolen your money.She hasgone home.瑪麗不可能偷你的錢,她回家去了.

三、“can+have+done”表示對(duì)過去行為的懷疑,用于疑問句,譯成“可能做過……嗎?”

There is no light in the room.Can theyhave gone out?屋里沒有燈,他們可能出去了嗎?

四、“could+have+done”是虛擬語(yǔ)氣,表示對(duì)過去事情的假設(shè),意思是本來能夠做某事而沒有做.

He could have passed the exam,but he wastoo careless.本來他能夠通過考試,但是他太粗心.

五、“may+have+done”表示對(duì)發(fā)生過的事情的推測(cè),意思是“可能已經(jīng)”或“也許已經(jīng)”,用于肯定句中.

—What has happened to George?

—I don't know.He may have got lost.

—喬治發(fā)生了什么事?

——我不知道,他可能迷路了.

六、“might+have+done”表示對(duì)過去事情的推測(cè),might與may意思相同,但可能性更小.多用于虛擬語(yǔ)氣結(jié)構(gòu)中.

He might have given you more help,eventhough he was busy.他或許會(huì)多給你一些幫助,即使他很忙.

七、“would+have+done”虛擬語(yǔ)氣,表示對(duì)過去事情的假設(shè),意思是“本來會(huì)做”.

Without your help,I wouldn't haveachieved so much.沒有你的幫助,我是不會(huì)取得如此大的成績(jī).

八、“should+have+done”意思是“本來應(yīng)該做某事,而實(shí)際沒做.”“shouldn't+have+done”表示本來不應(yīng)該做某事,而實(shí)際做了.含有指責(zé)對(duì)方或自責(zé)的含意.

Look,Tom is crying.I shouldn't have beenso harsh on him.看,湯姆哭了,我本來不應(yīng)該對(duì)他如此嚴(yán)厲.

九、“ought to+have+done”表示過去應(yīng)該做而實(shí)際并沒有做,譯成“理應(yīng)做……”,往往表示遺憾.與“should+have+done”用法基本一樣.

I ought to have gone home last Sunday.我理應(yīng)上星期日回家.

十、“need+have+done”表示本來需要做某事而沒有做.“needn't+have+done”則表示“本來不需要做某事而做了”.

I needn't have bought so much wine—only fivepeople came.我本來沒有必要買這么多酒,只來了五個(gè)人.