牛津译林版 2020 必修二

Unit4   Grammar and usage 课中

高中英语情态动词基本用法和考点归纳

情态动词有can (could), may (might), must, have to, shall (should, will (would), dare (dared), need (needed), ought to等。 情态动词无人称和数的变化;不能单独使用，必须与其后的动词原形构成谓语。

一、can和could

1.“能够”，表示能力(体力、知识、技能)can的过去式是could。

①To our surprise, she can drive a car but can’t ride a bicycle.

②He could speak several languages when he was young.

2.“能够”，表示建议或请求他人许可。

①--Can I go now?

-- Yes, you can. / No, you can’t.

此时可与may互换。在疑问句中还可用could, might代替，不是过去式，只是语气更委婉，不能用于肯定句和答语中。

②-- Could I come to see you tomorrow?

-- Yes, you can. ( No, I’m afraid not. )

3.表示推测(惊讶、怀疑、不相信的态度)，用于疑问句、否定句和感叹句中。

①He can’t be sleeping now, for the light is on.

②Can this be true?

4.can be +形容词，表示“有时会”

It can be as hot as 40℃ in my hometown in summer.

5.be able to 通常表示能做并且已经做了的事，can/could仅表示能力。

如：

①I was able to swim to the bank when the ship sank.

② I could lift the heavy box.

二、may/might

1.表示请求和允许。might比 may语气更委婉，而不是过去式。否定回答时可用can’t或mustn’t，表示“不可以，禁止”。

①--Might/ May I smoke in this room?

-- No, you mustn’t.

②Might I ask a question?

2.表示可能性。might的可能性较小。

①The phone is ringing. It may be Tom. He said he would phone me.

②It might be true.

③Your mother may /might not know the truth.

3.用于祈使句，表示祝愿。

May you succeed!

4.may/might as well “不妨，最好”

I am too busy now. You may as well ask him for help.我现在太忙了，你不妨去求助于他。

三、shall/should/ought to

shall的用法

1.shall用于一、三人称，表示征求对方的意见。

Shall we go to the cinema tonight?今晚去看电影好不好?

2.shall 用于第二、三人称，表示说话人给对方的命令、警告、允诺或威胁。

①You shall fail if you don’t work hard.(警告)

②He shall have the book when I finish it.(允诺)

③He shall be punished.(威胁)

should的用法

1.“应该”---表示建议或劝告     

You should give up smoking.

2.“应该”---表示推测   

It’s too late. He should be sleeping now.

3.表示一种惊讶语气，译为“竟然，居然”

I am so shocked that he should talk to his parents like that.他竟然那样对父母讲话，太让我震惊了。

ought to表示“应该”，更强调一种责任或义务

We students ought to offer our seats to the old when taking a bus.

在公交车上我们学生应该给老人让座。

四、will/would

1) 表示请求、建议等，would更委婉。

Will / Would you pass the dictionary to me, please?

2) 表示意志、愿望和决心。

①I will never do that again.

②They asked him if he would go abroad.

3) would表示过去反复发生的动作或某种倾向。would表示过去习惯时比used to正式，且没有“现已无此习惯”的含义。

①During the vacation, he would visit me every other day.

②The wound would not heal.

4)表示某种倾向性Fish will die without water.     The door won’t open.

五、must

1.表示必要性。如：

All passengers in the bus must wear seat belts.

2. must构成的一般疑问句，肯定回答用must，否定回答用needn’t或者don’t have to。如：

—Must we finish our work today?

—Yes，you must finish it as quickly as possible.

—No，you don’t have to/No，you needn’t.

3. must的否定形式mustn’t表示“禁止，不许”。如：

You mustn’t enter the stadium without a ticket.

4.表示“偏要”，常用于疑问句中，表示说话人的反感或厌烦。

如：Must you play the piano at such a late time? It’s midnight.

六、need/dare

1) dare作情态动词用时, 常用于疑问句、否定句和条件从句中, 过去式形式为dared。

①How dare you say I’m unfair?

②He daren’t speak English before such a crowd, dare he?

③If we dared not go there that day, we couldn’t get the beautiful flowers.

2) need 作情态动词用时, 常用于疑问句、否定句。在肯定句中一般用must, have to, ought to, should代替。

①You needn’t come so early.

② -- Need I finish the work today?

-- Yes, you must. / No, you needn’t.

3) dare和 need作实义动词用时， 有人称、时态和数的变化。在肯定句中，dare后面常接带to的不定式。在疑问句和否定句中，dare后面可接带to或不带to的不定式。而need后面只能接带to的不定式。

①I dare to swim across this river.

②He doesn’t dare (to) answer.

③He needs to finish his homework today.

七、情态动词+have done的用法总结

1.could have done 表示“本来能做但却没做”。

couldn’t have done 多用于语气强烈的否定,意为“过去不可能做过”

eg：

①He could have passed the exam, but he was too careless.他本来能够及格的，但是他太粗心了。

②The accident could have been avoided; the driver couldn’t have slowed down.这事故本来是可以避免的;司机肯定没减速。

2.may/might have done 意为“可能做过”。

might 所表示的可能性比较弱

might have done 还可表示“本可能做而实际上未做”,含有轻微的责备语气。

eg：

You might have given him more help, though you were busy with your work.

你本来可以给他更多的帮助,尽管你工作很忙。

3.must have done 意为“(过去)一定做过”,只用于肯定句。

eg：It must have rained last night, for the ground is wet.

昨晚一定下雨了,因为地面是湿的。

4.can’t have done 意为“(过去)不可能做过”

eg：Mr smith can’t have have gone to Beijing, for I saw him in the library just now.

5.should/ought to have done “本该做某事而实际上未做”;

should not have done/ ought not have done 表示“不该做某事反而做了”。

eg: Look, Mary is crying. I should’nt /oughtn’t have spoken to her so rudely.

6.needn’t have done “本来不必做某事而实际上却做了”。

eg: I got up early, but I needn’t have done so, because I had no work to do that morning.

我起床起得很早，但我本来不必起那么早的，因为我那天早上没什么事做。

情态动词练习题

一、选词填空

二、单句写作