情态动词（Modal Verbs)

情态动词表示说话人对某一动作或状态的态度，认为“可能”、“应当”、“必要”等等。但本身词义不完全，不能单独作谓语动词，必须和动词原形连用。情态动词没有人称和数的变化。

may and might can and could will and would shall and should must and can’t

may and might

1 ） 表示可能性（ possibility） ,用于对现在，过去或将来的推测，暗示不确定。 might 不是 may的过去式，它所表示的可能性比 may小，含较多的怀疑。

He may be very busy now. (可能性较大 )He might be very busy now. (可能性较小 )

may and might

2 ） 表示许可（ permission），表示允许别人做某事，也可征求对方的许可。

He may go now.We may keep the book for two weeks.3 ） 用于祈使句，表示祝愿。May you succeed!May you have a nice trip!

may sb. +v

can and could

1)  表示能力（ ability），指有能力做某事，意为“能够”。例如：

注意：表示现在，将来“能够”可用 be able to 替换。表示过去“能够”并成功了只能用 was/ were able to, 不能用 could 。例如

My grandma is over eighty, but she can/ is able to read without glasses.

We can/ will be able to talk about the matter later. I talked with her for a long time, and at last I was

able to make her believe me.(不能用 could)

can and could

2) 表示请求（ request ）或（ permission) 意为“可否”、“可以”。 Could 比 can 更有礼貌，在此不是 can 的过去式。

Can you wait a moment please? Liz, can you do me a favor? Excuse me, could you tell me the way to the station? I wonder if you could help me. (request) ---- Could I use your phone?

----Yes, of course. You can. Do you think I could borrow your bike? (permission)

can and could

3) 表示可能性 （ possibility ）a. can “ ”表示泛指的 可能 ，并非说话者主观认为的可能性，即并非说话者的主观猜测，指逻辑上的可能性。

Accident can happen to any drunken driver. b. 表示说话者主观猜测，只能用与否定句或疑问句中。例如：

It can’t be my father. He is now in England. ----Can it rain tomorrow? ----No, it can’t.

may, might, can, could

1. They (can/might) ___________be away for the weekend but I’m not sure.

2. You (may/might) __________leave now if you wish.

3. (could/may) __________you open the window a bit, please?

4. He __________be from America, judging by his accent.

5. (may/can) ___________you swim? 6. Listen, please. You (may not/might not)

_________________ speak during this exam.

might表示猜测

may表示许可

could表示请求

may表示猜测

Can 表示能力

may not表示不允许

may, might, can, could

7. They (can not/may not) _______________ still be out, the light is on in the house.

8. You (couldn’t/might not) _________________ smoke on the bus.

9. You (can/might) ___________ be right, but I’m going back to check it.

表示许可

couldn’t

can not表示猜测 (不可能 )

might表示猜测

will and would 1 ）表示意愿 表示愿意做或主动提出做，如意志 ,愿望或决心 That bag looks heavy, I’ll help you with it. ( offering to do sth) ---- You know that book I lent you. Can I have it b

ack if you’ve finished with it?---- Of course. I’ll give it to you this afternoon.

(agreement) Thanks for lending me the money, I’ll pay you bac

k on Friday. (promise)  

will and would

2）表示习惯 (habit, custom)This old man is strange. He will sit for hours

without saying anything. We would sit around Grandpa after supper,

listening to his stories.3）表示请求（ request） , 用于第二人称 , would 比 will 更委婉。 例如：

Will you come this way, please?Would you open the window?

shall and should

1） shall 的用法a.shall 在疑问句中用于第一，第三人称，表示征求对方的意见。

Shall we put off the sports meeting until next month? Shall Tom go there with me tomorrow? b.shall 用于第二，第三人称，表示说话人给对方的命令，警告，允诺或威胁。 You shall fail if you don’t work harder. （警告） He shall have the book when I finish reading it. (允诺 ) He shall be punished. (威胁 )

shall and should

2) should 的用法a. should 表示劝告、建议、命令。 You should go to class right away.b. should 表示期待，用于表达合理推断(prediction “ ” ，意为 应该 )，或明显的结果

“ ”（意为 可能 ）且所期待的事几乎是事实。 It is three o’clock, the football game should begin

now. Mary took dancing lessons for years, so she should be

an excellent dancer.

must and have to

1.must用于一般问句中 ,肯定回答用 must否定式用  needn’t或 don’t have to，  “ ”做 不必 ,mustn’t表“ ”示 禁止，不允许

 — Must I finish all assignments at a time? —Yes, you must. No, you needn't. 2. “ ”表示 必须 这个意思时， must 和 have to 稍有区别。 must着重说明主观看法， have to 强调客观需要。另外， have to 能用于更多时态。

I don’t like this TV set. We must buy a new one.

There was no more bus. They had to walk home.

must and can’t

must “ ” “ ”用来表示 命令 、 推测 等含义。 1）表示规定、指令 表示规定、指令时主要指客观上的法律、条文规定，常常翻译

“ ”为 应该、必须 之类意思。 mustn't表示禁止 You must have a passport if you want to go abroad. 2) 表示主观的命令、禁止 表示主观的命令、禁止时，主要指说话者主观的命令或强烈的劝告。

You can go out with your friend but you must come back before 11 at night.

----Must I hand in the exercise today?----No, you needn’t. 。

must and can’t

3）表示猜测，语气非常肯定，近乎确定的意味，……一般用于肯定句，意为肯定 。其否定为 can’t ，

…意为不可能 ... 。 You must be ill. I can see it from your face. He can’t be at home. I saw him in the classroom

just now.

Not sure Very sure

He might be in the classroom.

He may be in the classroom.

He could be in the classroom.

He should be in the classroom.

He must be in the classroom.

情态动词的猜测用法

1. We __________ smoke here, because the worker is carrying some petrol.

2. It is dangerous. You __________ leave the room immediately.

3. He ___________ go hiking with friends at weekends when young.

4. Write to me when you get home.---I ___________.

5. --Need I hand in my exercise book at once?--Yes, you__________.

6. You have been working all day. You __________ be very tired.

7. It is a long time since we met last time. You __________ come and see us more often.

8. Why don’t you try on this dress? It _________ look nice on you.

will, would, shall, should, must:mustn’t

should

would

will

mustmust

should

will

表示禁止 ,不许可

表示建议 ,命令

表示过去习惯

表示意愿

表示必须 表示肯定猜测

表示建议

表示将会 ,一定会

Group work

• Choose one of the following situations to create a short dialogue using modal verbs.

• Situation A: In a library. Ask the librarian if he can help to find a book relating to some specific topics, whether they can be renewed or not, and how to do if the books are lost. (“Could you please find…?” “May I …?” “You mustn't…”)

• Situation B: A doctor gives a patient some advice. (“You should…”)

• Situation C: In a park by a lake. Discuss that one should not destroy the environment. (“You should…”, “You shouldn't’ …”, “You mustn't’ …”)

• Situation D: Requesting an appointment. (“Will you…?” “Shall I …?”)

Group work

• Situation E: You have to go to buy food and gifts for Spring Festival. In pairs, one as the shop keeper and the other as the customer, offer and request the items you need. Use these expressions to help you.

• Would you like …? Could I have …?• Might I suggest …? May I see …?• You should try …? Could we look at …?• Can you see …? We might take …?

Sample dialogue• In the supermarket a customer is talking

with the salesman.A: Hello, I need to buy some things for the Spring Festival.

B: May I suggest these gifts for the children? They are very popular.

A: They are pretty, but could I have a look at the red paper envelopes on the shelf?

B: Sure, would you like these ones? They are less expensive.

A: That’s fine. I’ll take twelve of them. May I see what your pork is like? I need to make dumplings.

B: Of course, it’s over there. You should try some of the cabbage that just arrived. It’s very fresh.

A: Ok, could I have three cabbages and a kilo of pork? I also need some flour.

B: Can you see the flour down there? Please take what you need. Thanks for coming in, and have a good holiday.

1.---There were already five people in the car but they managed to take me as well. ---It ____a comfortable journey. ( ) A. can't be B. mustn't have been C. shouldn't be D. couldn't have been

D

2.The fire spread through the hotel very quickly but everyone ___ get out. ( ) A. had to B. would C. could D. was able to

D

3. Peter ___ come with us tonight, but he isn’t very sure.

A.must B. can C. may D. will

C

4. --- Could I call you by your first name? --- Yes, you____.

A. will B. could C. may D. might

C

5. Sorry, I ’m late. I ___ have turned off the alarm clock and gone back to sleep again.

A.might B. should C. can D. will

A

6.--Excuse me, but I want to use your computer to type a report.--You ____ have my computer if you don’t take care of it.A. shan’t B. might not C. needn’t D. shouldn’t

A

7. ---When can I come for the photos ? I need them tomorrow afternoon. ---They _____be ready by 12 : 00 . A. can B. should C. might D. need

B

8. With so much work on hand, you ____to see the game last night. A. mustn’t go B. could have goneC. shouldn’t go D. shouldn’t have gone

D

9.Johnny, you ______play with the knife, you ____hurt yourself. ( )A. won't ; can't B. mustn't ; mayC. shouldn't ; must D. can't ; wouldn't

B

10. I missed the bus, so I ___ go home on foot.

A. must B. may C. can D. had to

D

表示“能力”

表示“推测”

表示“许可；要求”

表示“建议”和“义务”

can must can must

could should could have to

could may need

may might Shall I …?

might must

can’t shouldn't

mayn’t mustn't

mightn’t Would you like…?

Can …? Will you please …?