2016年6月英語(yǔ)四級(jí)語(yǔ)法基礎(chǔ)：情態(tài)動(dòng)詞

1、情態(tài)動(dòng)詞的完成式

1)must have done——表示對(duì)過(guò)去的事情較有把握

的、肯定性的推測(cè)，常譯為“一定，準(zhǔn)是，肯定”，其否定形式是can’t/couldn’thave done，意為“決不可能，不太可能”。

e.g. Since the ditch is full of water, it must have rained last night.

2)should/ought to have done——表示過(guò)去應(yīng)該做的

卻沒(méi)有做，常含有后悔、責(zé)備、埋怨的口吻，意為“本應(yīng)該”，“應(yīng)該就好了”; e.g. With all the work finished, I should have gone to your birthday party last night.

3)shouldn’t/ought not to have done——表示過(guò)去不該

做的事卻給做了，也常含有責(zé)備、不滿之意，意為“本不該”。

e.g. You shouldn’t have gone back to work yesterday without the doctor’s permission.

4)may/might have done——表示對(duì)過(guò)去的事情的推

測(cè)，但不十分有把握，意為“可能，或許已經(jīng)”。 e.g. A traffic accident happened yesterday and a driver may have been hurt.

5)could have done——表示過(guò)去有可能或有能力做某

事，而實(shí)際未做、未能實(shí)現(xiàn)的事;有時(shí)也表示輕度批評(píng)，意為“本來(lái)可以，完全可以”。 e.g. The gas leakage could have been avoided if the

gas company took immediate measures after the warning call.

6)needn’t have done——表示過(guò)去做了某事，但沒(méi)有做的必要，意為“其實(shí)沒(méi)有必要”。 e.g. I needn’t have bought all that wine——only three people came.

2、可作情態(tài)動(dòng)詞用的短語(yǔ)

would rather, would sooner, would (just) as soon, had rather, had better, had sooner, cannot but, may/might as well

[例1]You all those calculations! We have a computer to do that sort of thing.

A. needn’t have done B. must not have done

C. shouldn’t have done D. can’t have done

[例2]I to him because he phoned me shortly afterwards.

A. ought to have written B. must have written

C. couldn’t have written D. needn’t have written

[例3]You those letters. Why didn’t you

A. should post B. must have posted

C. should have posted D. ought to post

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