高中英语语法讲解： 情态动词

高中英语语法讲解：情态动词

概述

1.共有10个情态动词：can/could, may/might, will/would, shall, should, ought to, must；2个

半情态动词need, dare

2.特点：（1）情态动词后加动词原形（即不带to的不定式）一起构成谓语；（2）没有人

称和数的变化；（3）多数情态动词有过去式，但其过去式有时并不表示时态，而只起“委婉或不确定语气”的作用。

Would you do me a favour? She may/might be watering the flowers now.

3.情态动词在句子中可发挥不同作用，如表能力，表责任与义务，表推测，表征求允许，

表请求，表建议，表语气态度等等

He can/could run 100 meters in 11 seconds.

You should/ought to/must work hard to win a gold medal.

Can/Could/May/Might I watch the Olympics tonight?

Will/Can/Could/Would you help me with my training?

He might/may/could/should/ought to/will/must watch the football match tonight.

I suggest that you should watch the opening ceremony.

Can this be true?

4.情态动词+do 表对一般现在或将来情况的推测

情态动词+ be doing 表对正在发生的事情的推测

情态动词+have done 表对过去已经发生的事情的推测

一、can/could 的用法

1.表能力

(1) can do现在一般的能力(2) could do过去一般的能力(3) could have done过去有能

力做但没做具体某事（4）was/were able to do = managed to do/ succeeded in doing 过去有能力做且做了具体某事。注：be able to可用于各种时态、不定式中或其他情态动词之后

I can speak fluent English now, but I couldn't (不能)ten years ago.

He could have fled (flee)the city before the war broke out, but he stayed with his sick wife.

You could have done the work better, but you were too careless.

The fire spread through the hotel quickly but everyone was able to get out.

2．表示请求和允许。(could更委婉，但答语中须用can)

--Can / Could I use your computer? --Yes, of course you can. / No, I’m afraid you can't.

3.表推测

(1) can在肯定句+现在时中，表示理论上的可能性，对某件宽泛的事情而言，并不表示

具体某事是否会发生，可译为“有时会，理论上可能”。注：若要表示具体某事发生的可能性，要用could, may, might。

More accidents can happen on such rainy days.

A wise man can make mistakes.

It can be as hot as 40℃ here in summer.

Baby are lovely, but sometimes they can be tiresome.

Peter could/may/might come with us tonight, but he isn’t sure yet.

(2) can/could在否定句和疑问句中，可表示某事实际发生的可能性，译为“可能(吗)”，“不

可能”。

Listen, someone is coming. Can/Could it be Tom?

My wallet is nowhere to be seen. Who can/could have taken it away?

It is 10 o'clock in the morning. Tom can't/couldn't be sleeping now. 不可能正在做某事The streets are all dry. It can't/couldn't have rained last night. 过去不可能已经做某事

4.固定用法：

(1) can not/never…too/enough“再怎么…也不过分，越…越好”

I can never thank you enough. You can't be too careful.

You can never remember too many words.

(2) can't + 比较级“不能更...，非常...”

I can't agree more. The film couldn't' t be more boring

(3) cannot but do sth. 不得不，只好I cannot but admire your bravery.

(4) can't help doing sth 情不自禁做；can't help (to) do sth 不能帮忙做

二、may/might的用法

1．表示请求和允许，译为“可以”。might更委婉，否定回答可用may not/ can't/ mustn't。

--May/Might I use your pen? --Yes, you may./--No，you may not/ can't/ mustn’t．

2．表推测, 表具体某事实际发生的较小的可能性；否定句中may/might not 译为“可能不”

--Are you coming to Jeff’s party? --I’m not sure. I might go to the concert instead.

She may/might not know he is a millionaire.

3．may表示祝愿或希望。

May God bless you! May you return in safety！

May we never forget each other！

4.固定搭配：

(1) may well do sth很可能

Her appearance has changed so much that you may well not recognize her.

(2) may/might as well do sth 最好

You may as well tell me the truth. We may as well stay where we are.

(3) may/might have done

①可能已经做了某事（表推测）

She isn’t here. She may/might have missed the first train in the morning.

He hasn’t come. He may/might not have finished the work.

②本来可能做，但实际没有做（含轻微责备语气）

You should not have climbed the tree. You might have hurt yourself.

You might have given him more help, even though you were busy.

三、must 的用法

1.表示责任与义务，译为“必须，一定”，否定mustn't表示“禁止，不允许”