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 .我们得在十点钟到那里。

We will have to reconsider the whole thing.

这一切我们将不得不重新加以考虑。

have to 的否定式：don’t have to do 表示“不必做……”之意。

4.must 的主要用法。

1)表示必须、必要

We must do everything step by step .我们必须按部就班地做一切事情。

Why must you always bother me? 为什么你偏要打扰我呢。

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. 他一定是个诚实的男孩。

This must be your room. 这一定是你的房间。

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?明天我必须去吗？

Yes, please.是的，请吧！

No , you needn’t. 不，你不必去。

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.她以前一定学过英语。

3.may 的用法

1)表示请求、可以、允许。

You may drive the tractor. 你可以开那台拖拉机。

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　 (可能不)

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 no 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.

你还是原地待着好。(may as well 有“还是……的好”的含义)

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.

她说他可以拿她的词典去用。

除在间接引语中外，might一般不表示过去的“可能”与“许可”。表过去的“可能”可用could，表过去的“许可”可用were (was) allowed to。

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.

电熨斗会有危险，它可能电着人。

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。

It may have been true. 这事也许是真的。

He might not have settled the question. 他可能尚未解决那个问题。

2.could的用法

1)表过去的可能和许可，(多用于间接引语中)

At that time we thought the story could not be true.

那时我们认为所说的事不可能是真的。

Father said I could swim in the river.

爸爸说我可以在河里游泳。

2)表过去的能力

I could swim when I was only six.

我刚六岁就能游泳。

Could在肯定句中表示过去的能力时，常表抽象的一般的能力。

He could be very naughty when he was a child.

他小时候会是很顽皮的。

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.

他会记得那时吗?

I’m afraid I couldn’t give you an answer today.

恐怕我今天不能回答你。

The teacher said you could go to the store for sweets.

老师说你可以去商店买糖。

3)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可能完成而却未完成的动作。

Can they have won the basketball match？

他们赢了那场篮球赛吗？

What you referred to just now can have made her very sad.

你刚刚所谈到的可能令他很伤心。

You could have completed the task a little earlier.

你本来能早点完成任务的。(但事实上并没有提前完成任务)

I could have passed my examination easily but I made too many stupid mistakes.

我本可以轻易通过考试，但我犯了太多不该犯的错误。

如表具体做某一件事的能力时，则须用 be able to .

He was able to translate the article without a dictionary.

他可以不用词典翻译那篇文章。

Can表示一贯的能力 ，be able to表示客观能力和通过努力可以达到的能力

I can’t swim. But I am sure I will be able to swim through more practicing.

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

When the boat sank he was able to swim to the bank

　 1-10 BDACDBDBCB　 11-20　 CDCBDBBCCB　 21-30　 DDCABDABCA

第六章　 情态动词

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

can表能力时意味着凭体力或脑力或技术等可以无甚阻力地去做某事。

I can climb this pole. 我能爬这根杆子。

He is only four , but he can read. 他只有4岁，但已认得字了。

Fire can’t destroy gold. 火烧不毁金子。

因为can不能和其他助动词连用，所以表示将来式时用will be able to

You will be able to skate after you have practiced it two or three times.

你练习两三次后就会溜冰了。

2)表可能性

多用于否定与疑问结构中，但也可用在肯定句中。

Can the news be true? 这消息可能是真的吗？

It can’t be true. 它不可能是真的。

What can he possibly mean? 他可能是什么意思？

can 用在肯定句中表示理论上的可能性(一时的可能)。

A horse in the center of London can cost a lot of money.

Attending the ball can be very exciting.

The road can be blocked. 这条路可能会不通的。

may 在肯定句中表示现实的可能性。

The road may be blocked. 这条路可能不通了。

3)表示允许(和may意思相近)常见于口语。

Can (May) I come in ? 我能进来吗？

Can I smoke here ? 我可以在这里抽烟吗？

1.If it is fine tomorrow, we ______ a football match.

a. have　　 b. will have　　 c. has　　 d. shall has

2.When he was at school, he ______ early and take a walk before breakfast.

a. will rise　 b. shall rise　 b. should rise　　 would rise

3.In the past 30 years China ______ great advances in the socialist revolution and socialist construction.

a. has made　 b. have made　 c. had made　 d. having made

4.I ______ go to bed until I ______ finished my work.

a. don’t/had　 b. didn’t/have　　 c. didn’t/had　　 d. don’t/have

5.______ you think he ______ back by dinner time?

a. Do/have come　 b. Did/will have come　　 c. Does/will come　　 d. Do/will have come

6.He said that he dropped his bag when he ______ for the bus.

a. was runing　 b. was running　 c. were running　 d. is running

7.No sooner ______ he arrived home than he ______ to start on another journey.

a. has/was asked　 b. have/were asked　 c. had/is asked　 d. had/was asked

8.“______ you give me a room for the night?” I asked on arriving at the hotel.

a. Should　 b. Can　 c. Might　 d. May

9.There are nine of them, so ______ get into the car at the same time.

a. they may not at all　 b. all they may not　 c. they can’t all　 d. all they can’t

10.“We didn’t see him at the lecture yesterday.” “He ______ it.”

a. mustn’t attend　　　　　　 b. cannot have attended 

c. would have not attended　 d. needn’t have attended

11.“You realize that you were driving at 100 mph, don’t you?”

 “No, officer. I ______. This car can’t do more than 80.”

a. didn’t need to be　 b. may not have been　 c. couldn’t have been　 d. needn’t have been

12.he was a good runner so he ______ escape from the police.

a. might　 b. succeeded to　 c. would　　 d. was able to

13.If they ______, our plan will fall flat.

a. are co-operating　 b. had not co-operated　 c. won’t co-operate　 d. didn’t co-operate

14.I hoped ______ my letter.

a. her to answer　 b. that she would answer　 c. that she answers　 d. her answering

15.He ______ live in the country than in the city.

a. prefers　 b. likes to　 c. had better　　 d. would rather

16.______ to see a film with us today?

a. Did you like　 b. Would you like　 c. Will you like　 d. Have you liked

17.I’m sorry, but I had no alternative. I simply ______ what I did.

a. must do　 b. had to do　 c. ought to have done　　 d. have to do

18.“Time is running out,______?”

a. hadn’t we better got start　　 b. hadn’t we better get start

c.hadn’t we better get started　 d. hadn’t we better not started

19.No one ______ that to his face.

a. dares say　 b. dares saying　　 c. dare say　　 d. dare to say

20.The students in the classroom ______ not to make so much noise.

a. need　 b. ought　　 c. must　　 d. dare

21.You ______ last week if you were really serious about your work.

a. ought to come　 b. ought to be coming　 c. ought have come　　 d. ought to have come

22.The elephants ought ______ hours ago by the keepers.

a. to be fed　 b. to feed　　 c. to being fed　　 d. to have been fed

23.“I wonder why they’re late.” “They ______ the train.”

a. can have missed　 b. could miss　 c. may have missed　　 d. might miss

24.“Tom graduated from college at a very young age.” 

　“He ______ have been an outstanding student.”

a.　　　 must　 b. could　 c. should　 d. might

25.You ______ the examination again since you had already passed it.

a. needn’t have taken　 b. didn’t need to take　 c. needn’t take　 d. mustn’t take

26.He is really incompetent! The letter ______ yesterday.

a. should be finished typing　　 b. must be finished typing

c.must have finished typing　　 c. should have been finished typing

27.The boy told his father that he would rather ______ an astronaut.

a. become　　 b. to become　　 c. becoming　　 d. became

28.When we reached the station, the train had still not arrived; so we ______.

a. needed not to hurry　　　　 b. needn’t have hurried　　 

c. need not to have hurried　　 d. didn’t need to hurry

29.Since your roommate is visiting her family this weekend,_____ you like to have dinner with us tonight?

a. will　 b. won’t　 c. wouldn’t　　 d. do

30.He was afraid what he had done ______ a disastrous effect on his career.

a. might have　　 b. could be　　 c. have been　 d. shall be

6. 短语动词

　动词加小品构成的起动词作用的短语叫短语动词。例如：

　Turn off the radio.　把收音机关上。(turn off是短语动词)

　短语动词的构成基本有下列几种：

1)动词+副词，如：black out；

2)动词+介词，如：look into；

3)动词+副词+介词，如：look forward to。构成短语动词的副词和介词都统称为小品词

5.助动词should, would的用法

1)should无词义，只是shall的过去形式，与动词原形构成过去将来时，只用于第一人称。例如：

　　 I telephoned him yesterday to ask what I should do next week. 我昨天给他打电话，问他我下周干什么。

　　 比较："What shall I do next week?" I asked. "我下周干什么？"我问道。

　　 可以说，shall变成间接引语时，变成了should。

2) would也无词义，是will的过去形式，与动词原形构成过去将来时，用于第二、第三人称。例如：

　　 He said he would come.　 他说他要来。

比较："I will go," he said. 他说："我要去那儿。"变成间接引语，就成了He said he would come。原来的will变成would，go变成了come.。

4. 助动词shall和will的用法

　 shall和will作为助动词可以与动词原形一起构成一般将来时。例如：

　　I shall study harder at English.　 我将更加努力地学习英语。

　　He will go to Shanghai.　他要去上海。

说明：在过去的语法中，语法学家说shall用于第一人称，will 只用于第二、第三人称。现在，尤其是在口语中，will常用于第一人称，但shall只用于第一人称，如用于第二、第三人称，就失去助动词的意义，已变为情态动词，试比较:

　 He shall come.　他必须来。(shall有命令的意味。)

　 He will come.　他要来。(will只与动词原形构成一般将来时。)

3.助动词do 的用法

1)构成一般疑问句。例如：

　　 Do you want to pass the CET?　你想通过大学英语测试吗？

　　 Did you study German?　你们学过德语吗？

2)do + not 构成否定句。例如：

　　 I do not want to be criticized.　 我不想挨批评。

　　 He doesn't like to study.　 他不想学习。

　　 In the past, many students did not know the importance of English.　

过去，好多学生不知道英语的重要性。

3) 构成否定祈使句。例如：

　　 Don't go there.　不要去那里。

　　 Don't be so absent-minded.　不要这么心不在焉。

说明： 构成否定祈使句只用do，不用did和does。

4)放在动词原形前，加强该动词的语气。例如：

　　 Do come to my birthday party.　一定来参加我的生日宴会。

　　 I did go there.　我确实去那儿了。

　　 I do miss you.　我确实想你。

5)用于倒装句。例如：

　　 Never did I hear of such a thing.　 我从未听说过这样的事情。

　　 Only when we begin our college life do we realize the importance of English. 进了大学以后，我们才认识到英语的重要性。

说明： 引导此类倒装句的副词有never, seldom, rarely, little, only, so, well等。

6)用作代动词。例如：

　　 ---- Do you like Beijing?　--你喜欢北京吗？

　　 ---- Yes, I do.　--是的，喜欢。(do用作代动词，代替like Beijing.)

　　 He knows how to drive a car, doesn't he? 他知道如何开车，对吧？