情态动词的用法总结

下面是小编整理的一些关于情态动词的用法总结，欢迎大家阅读!

possibility: can / could, may / might

certainty: must, will, should

ability: can / could, be able to

permission: can / could, may / might

requests: can / could, will / would

suggestions: could / may /might, shall

necessity: must, have to, have got to, need

advice: ought to, had better

　　情态动词的语法特征

1. 情态动词没有人称和数的变化,即情态动词第三人称单数不加- s (have to, have got to, be able to 除外)。

2. 情态动词不能表示正在发生或已经发生的事情,只表示期待或估计某事的发生。

3. 情态动词本身具有一定词义, 但意思不够完整, 不能单独做谓语, 后接动词原形一起构成谓语部分 (ought to, have to/have got to, be able to除外)。

4. 情态动词无非谓语形式,即无不定式、分词等形式。

　　Sum up

1. can和be able to

1) can (could) 表示能力、可能, 只用于现在式和过去式

2) be able to可以用于各种时态。

只用be able to的情况：

a. 位于助动词后。

b. 情态动词后。

c. 表示过去某时刻动作时。

d. 用于句首表示条件。

e. 表示成功地做了某事时,只能用was/ were able to,不能用could。

注意:could还可不表示时态,只表示

1) 提出委婉的请求,回答中不可用could。

--- Could I have the television on?

--- Yes, you can. / No, you can’t.

2) 在否定、疑问句中表示推测或怀疑。

He couldn’t be a bad man.

2. may和might

1) 表示允许或请求;表示没有把握的推测;may 放在句首,表示祝愿。

e.g. May God bless you!

He might be at home.

注: might 表示推测时,不表示时态。只是可能性比may 小。

2) 成语:may/might as well,后面接不带to 的不定式，意为"不妨"。

e.g. If that is the case, we may as well try.

3. have to和must

1) 两词都是“必须”的意思, have to 表示客观的需要, must 表示说话人主观上的看法, 即主观上的必要。

e.g. My brother was very ill, so I had to call the doctor in the middle of the night.

He said that they must work hard.

2) have to有人称、数、时态的变化,而must只有一种形式。但must可用于

间接引语中表示过去的必要或义务。

e.g. He had to look after his sister yesterday.

3) 在否定结构中：don’t have to 表示“不必”; mustn’t表示”禁止”。

e.g. You don’t have to tell him about it. 你不必把这事告诉他。

You mustn’t tell him about it.　 你不能把这事告诉他。

　　4. 情态动词must表示推测

1) must用在肯定句中表示较有把握的推测,意为“一定”。

2) must表对现在的状态或现在正发生的事情的推测时, 后面通常接系动词be的原形或行为动词的进行时。

e.g. You have worked hard all day.

You must be tired.(对现在情况的推测判断)

He must be working in his office. 他一定在办公室工作呢。

比较: He must be staying there. 他现在肯定呆在那儿。 表推测

He must stay there. 他必须呆在那儿。不表推测

3) must 表示对已发生的事情的推测时, 要接完成时。

e.g. I didn’t hear the phone. I must have been asleep.

4) must表示对过去某时正发生的事情的推测, 后面要接不定式的完成进行时。

e.g. ---Why didn’t you answer my phone call?

---Well, I must have been sleeping, so I didn’t hear it.

5) 否定推测用can’t.

e.g. If Tom didn’t leave here until five o’clock, he can’t be home yet.

　　5.情态动词表示推测的用法

can, could, may, might, must 皆可表

示推测,其用法如下：

1) 情态动词+动词原形,表示对现在或将来的情况的推测,此时动词通常为系动词。

e.g. I don’t know where she is. She may be in Wuhan.

2) 情态动词+动词进行时, 表示对现在或将来正在进行的情况进行推测。

e.g. At this moment, our teacher must be correcting our exam papers.

3) 情态动词+动词完成时, 表示对过去情况的推测。

e.g. The road is wet. It must have rained last night.

4) 情态动词+动词的完成进行时, 表示对过去正在发生事情的推测。

e.g. Your mother must have been looking for you.

5) 推测的否定形式,疑问形式用can’t, couldn’t表示。

e.g. Mike can’t have found his car, for he came to work by bus this morning.

注: could, might表示推测时不表示时态,其推测的肯定程度不如can, may。

　　6.情态动词+have+过去分词

1) may (might) have + done sth., can (could) have + done sth. 表示过去,推测过去时间里可能发生的事情。

e.g. Philip may (might) have been hurt seriously in the car accident.

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

2) must have+done sth., 表示对过去时间里可能发生的事情的推测,语气较强,具有“肯定”的意思。

e.g. --- Linda has gone to work, but her bicycle is still here.

--- She must have gone by bus.

3) ought to have done sth.should have done sth.本应该做某事,而事实上并没有做; 否定句表示“不该做某事而做了”。

e.g. You ought to (should) have been more careful in this experiment.

He ought not to have thrown the old clothes away.(事实上已扔了。)

注: ought to 在语气上比should 要强。

4) needn’t have done sth. 本没必要做某事

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

5) would like to have done sth. 本打算做某事

e.g. I would like to have read the article, but I was very busy then.

　　7. 情态动词should和ought to

should 和ought to 都为“应该”的意思,可用于各种人称。

e.g. --- Ought he to go?

--- Yes. I think he ought to.

表示要求,命令时,语气由 should(应该)、(had better最好)、must(必须) 渐强。

　　8. 情态动词had better表示“最好”

had better 相当于一个助动词,它只有一种形式,它后面要跟动词原形。

had better (not) do sth.

e.g. It is pretty cold. You’d better put on my coat.

She’d better not play with the dog.

had better have done sth.

表示与事实相反的结果,意为“(过去)本来最好”。

e.g. You had better have come earlier.

　　9. 情态动词would rather表示“宁愿”

would rather (not) do

would rather…than…宁愿…而不愿

would sooner had rather had sooner表示"宁愿"、"宁可"的意思。

e.g. If I have a choice, I had sooner not continue my studies at this school.

　　10. will和would

1) would like to do = want to 想要

e.g. Would you like to go with me?

2) Will you…? / Would you like…?

表示肯定含义的请求劝说时,疑问句中一般用some, 而不是any。

e.g. Would you like some cake?

3) 否定结构中用will, 一般不用would, Won’t you是一种委婉语气。

e.g. Won't you sit down?

　　11. need和dare

这两词既可做实义动词用,又可做情态动词用。作为情态动词,两者都常用于疑问句,否定句和条件句。并注意回答用need 提问的句子时，肯定回答用must。

need 作实义动词时后面的不定式必须带to,而dare作实义动词用时, 后面的to时常可以被省略。

1) 实义动词: need+ n. / to do sth.

2) 情态动词: need,只用原形need后加do,否定形式为need not.

e.g. ---- Need you go yet?

---- Yes, I must. / No, I needn't.

3) need, want, require, worth(形容词)后面接doing也可以表示被动。

need doing = need to be done

　　Exercises

1. A left-luggage office is a place where bags ____be left for a short time, especially at a railway station.

A. should B. can

C. must D. will (B)

2. How ___ you say that you really understand the whole story if you have covered only part of the article?

A. can B. must

C. need D. may (A)

3. — The room is so dirty. ___we clean it?

— Of course.

A. Will B. Shall C. Would D. Do (B)

4. My English-Chinese dictionary has disappeared. Who ___ have taken it?

A. should B. must

C. could D. would (C)

5. — Is John coming by train?

— He should, but he ____ not. He likes driving his car.

A. must

C. need (D)

6. — I heard they went skiing in the mountains last winter.

— It ____ true because there was little snow there.

A. may not be B. won’t be

C. couldn’t be D. mustn’t be (C)

7. It has been announced that candidates __ remain in their seats until all the paper have been collected.

A. can B. will C. may D. shall (D)

8. — I hear you’ve got a set of valuable Australian coins. ___ I have a look?

—Yes, certainly.

A. Do B. May C. Shall D. shall (B)

9. Oh, I’m not feeling well in the stomach, I ___ so much fried chicken just now.

A. shouldn’t eat

B. mustn’t have eaten

C. shouldn’t have eaten

D. mustn’t eat (C)

10. I was really anxious about you. You ___ home without a word.

A. mustn’t leave

B. shouldn’t have left

C. couldn’t have left

D. needn’t leave (B)