高中情态动词的重难点突破
2011年11月02日 08:34
来源：本站原创
高中情态动词的重难点突破
一.概念:
情态动词是表示能力,义务,必须,猜测等说话人的语气或情态的动词.
二.相关知识点精讲:
1．can
1)表能力
He is only four , but he can read.
Fire can’t destroy gold.
2)表可能性
Can the news be true?
It can’t be true.
What can he possibly mean?
Attending the ball can be very exciting.
3)表示允许
Can (May) I come in ?
Can I smoke here ?
4)有时会
Training alone can be dangerous.
2.could的用法
1)表过去的可能和许可，
Father said I could swim in the river.
2)表过去的能力
I could swim when I was only six.
He could be very naughty when he was a child.
3)表“允许”。可表示委婉客气的提出问题或陈述看法
Could I use your bike?
Yes, you can.
4)Could/can+have done 结构表示对过去发生的事情的“怀疑”或“不肯定”。 could 加完成式还用于肯定句时一般表过去本可以完成却未完成的动作（虚拟）。
Can they have won the basketball match？
You could have completed the task a little earlier.
I could have passed my examination easily but I made too many stupid mistakes.
3.may 的用法
1)表示请求、可以、允许。
You may drive the tractor.
2)当回答由may 引起的问题时，否定答语要用must not,表示“不许可”、“不应该”、“不行”。
May I come in?
Yes, you may.
No,you can’t
No, you may not .
No ,you mustn’t
No ,you’d better not.
3) may /might 推测性用法 可能
He may be right.
He may not come today
He may /might come tomorrow.
注意 : (1)只用于肯定和否定句中,不用于疑问句中。
(2) might 比may可能性更小
He might get a job.
He may get a job.
(3) may not 可能不 can not不可能
He may not come
He can’t come
3)表建议（可和as well 连用）
You may（might）as well stay where you are.（may as well “还是……的好,不妨”
4)表祝愿
May you be happy!
might
1)表过去的“可能”和“允许”多用于间接引语。
She said that he might take her dictionary.
2)表现在的“可能”，其可能性要比may小。
Electric irons could be dangerous; they might give you a severe shock.
3)may (might) + have +done 表示对过去发生行为的推测，含有“想必”、“也许是”的意思；也许会做了某事但没做到（虚拟）
It may have been true.
He might not have settled the question.
4.must 的主要用法。
1)表示必须、必要
We must do everything step by step .
Why must you always bother me?
2)must be + 表语的结构，通常表示猜测，含有“一定”之意。（只用在肯定句中）
He must be an honest boy.
This must be your room.
3)must 的否定式有两个：当回答由must引起的问题时，否定答复要用needn’t或don’t have to 表示“不必”、“无须”、“用不着”、“不一定”的意义。当表示“不应该”、“不许可”、“禁止”时，就用must not。
Must I go tomorrow?
Yes, please.
No , you needn’t.
4)must +have +过去分词的结构，常用在肯定句中，表示对过去发生行为的推测，含有“一定”、“准是”的意思。否定和疑问句用can。
She must have studied English before.
5.have to的含义与must是很接近的,只是have to 比较强调客观需要，must着重说明主观看法。
I must clean the room.（主观想法）
I have to clean the room.（客观需要）
另外，have to 能用于更多时态：
We had to be there at ten .
We will have to reconsider the whole thing.
have to 的否定式：don’t have to do 表示“不必做……”之意。
6.ought to 的用法
Ought to 用于否定句，其否定形式可缩略为oughtn’t ，如：
You oughtn’t to smoke so much.
也可以用于疑问句，如：
Ought you to smoke so much?
7.shall的用法
1)用于第一人称征求对方的意见，如：
What shall I wear on the journey?
Shall we dance?
2)shall 用于第二、三人称时表允诺，警告，命令，威胁（现已少见），如：
She shall get her share.
You shall have it back tomorrow.
情态动词should一般不应被认为是情态动词shall的过去式，
3)“should+be+表语”的结构，表示推测或惊奇。例如：
They should be back by now.
I am sorry that she should be so careless.
4)“should+have+过去分词”的结构，表示过去该做而实际上尚未做的动作或行为；其否定则表示发生了不应该发生的行为。其同义结构“ought to have +过去分词”,表示过去“早应该”、“本当”之意，语气较强。例如：
I should have thought of that.
They should not have left so soon.
5) 在“It is natural (strange, natural, necessary, surprised, impossible, important ) that……”句型中，主语从句中的谓语动词要用should +动词原形”表示“理所当然”、“奇怪”、“必要”、“惊异”等的意思。在lest（以免）、for fear (that) (以防)、in case（以备万一）等之后也要用should+动词原形;在advise, sugest, order, demand, request 等的从句中should+do”例如：
It is necessary that he(should) be sent there at once.
It is strange that he should say so.
Let us go at once lest we should be late for the train.
8..will和would的用法
1）表示意志，决心或愿望。例如：
Surely we will support all the people in the world in their struggle for peace.
He would not let me try it .
2）用于第二人称作主语的疑问句中，表示对对方的请求，would的语气比will委碗
Would/will you kindly tell me the way to the station?
4）表可能性
This will be the book you are looking for.
She would be about 60 when she died.
9. need和dare的用法
情态动词need 实义动词 need
You need (not) do You (don’t) need to do
He need (not) do He needs (doesn’t need) to do
You needed (didn’t need) to do He needed (didn’t need) to do
You need (not) do You will (not) need to do
He need (not) do He will (not) need to do
句型 时态 动词
情态动词dare 实义动词 dare
肯定句 现在时 dare to 少用 dare/dares to do
过去时 dare to 少用 dared to do
否定句 现在时 daren’t/dare not do do/does not dare (to) do
过去时 dared not do did not dare (to) do
疑问句 现在时 Dare he do? Do you/Does he dear (to) do?
过去时 Dared he do? Did he dare (to) do
needn’t have v-ed 表示过去做了某事，但没有做的必要，意为“本没必要…”。例如：
You needn’t have waken me up; I don’t have to go to work today
10.表推测的情态动词句子的反意疑问句
He must/may be in the room, isn’t he?
He can’t be in the room, is he？
He must have finished the work, hasn’t he?
He may have done the work last night, didn’t he?
：情态动词+行为动词进行式
情态动词+行为动词进行式（即情态动词+ be + v-ing形式），表示推测或评论某动作现在是否正在进行。例如：
1）He must be playing basketball in the room.
2）She may be staying at home.
11.情态动词+行为动词完成进行式
情态动词+行为动词完成进行式（即情态动词+ have been + v-ing 形式），表示推测或评论过去某动作是否正在进行或一直在进行。例如：
1）They should have been meeting to discuss the problem.
2）He may / might have been buying stamps in the post office when you saw him.
13．用作情态动词的其他短语
would rather, would sooner, would (just) as soon, had rather, had better, had sooner, can not but, may (just) as well等可用作情态动词。例如：
1）The soldier would sooner die than surrender.
2）The brave soldier would as soon die as yield to such an enemy.
3）I’d rather walk than take a bus.
4）If you don’t like to swim, you may just as well stay at home.
注：这些短语后一般直接跟动词原形.would (had) rather, would (had) sooner, would (just) as soon后可跟that 引导的从句，that 常省去，从句要用虚拟语气。对现在和将来的假设用过去时，对过去的假设用过去完成时。例如：
1）I would rather you came on Sunday.
2）I would sooner you hadn’t asked me to speak yesterday.
三. 巩固练习:
1. _____ you ready?
(A) Are (B) Have (C) Will (D) Can
2. ____ here early?
(A) Will he (B) Was he (C) Did he be (D) Were he
3. I ___ happy about the price of eggs.
(A) am't (B) am not (C) do not (D) won’t
4. Since last year I____ him only once.
(A) have seen (B) have been seeing (C) see (D) was seeing
5. Donald ___ sixteen tomorrow.
(A) is being (B) going to be (C) shall be (D) will be
6. I ___ the story at all.
(A) don't like (B) like (C) am fond of (D) would like
7. I would rather ___ than play now.
(A) to study (B)am studying (C) study (D) studied
8. I'd rather you ___ anything about it for the time being.
(A) do (B) didn't do (C) don't (D) didn't
9. The car___much money.
(A) not cost (B) not have cost (C) isn't cost (D) didn't cost
10. I ___ like to eat fish.
(A) am (B) have (C) do (D) be
11. ___ repeat the question?
(A) Shall I (B) Will I (C)Would you like that I (D) Do you want that I
12. My teacher knows more than ___.
(A) my uncle knows (B) my uncle does
(C) they know (D)they don't know
13. He___to meet us at the station, but didn't see us.
(A) did go (B) did went (C) goes (D) had
14. Not only ____us light.
(A) does the sun give (B) the sun gives
(C) gives the sun (D) the sun does give
15. ____ you tell me what has happened?
(A) May (B) Must (C) Can (D) Could
16. Anne___tomorrow.
(A) can sing (B) can to sing (C) is going sing (D) going to sing
17. You___hand it in at once, you may hand it in tomorrow.
(A) needn't (B) may not (C) can't (D) must not
18. Tell the boy that he ___ in the river.
(A) swims (B) swim (C) swimming (D) to swim
19. Joan___play on Saturday.
(A) going to (B) can (C) is going (D) can to
20. Susan and I can go to the lecture ___.
(A) but neither can Charles (B) and so Charies can
(C) but Charles can't (D) and Charles also can
四.答案
1. (A) 2, (B) 3. (B) 4. (A) 5, (D) 6, (A) 7. (C) 8. (B) 9. (9) 10, (C)
11. (A) 12. (B) 13. (A) 14. (A) 15. (D) 16. (A) 17. (A) 18. (B) 19. (B) 20, (C)
