人教版高中英语必修3 Unit 2 Healthy eating 情态动词课件（共25张PPT）

(共25张PPT)
Period 4
Grammar
Modal Verbs
What ought we to do to stay slim?
You look tired. You _______ go to bed now.
should
You ___________ believe everything you read on the Internet.
shouldn’t
1. ought to语气稍重> should “应该” ，可用于各种人称。
You ought to (should) follow your friend’s advice.
多数情况下，两者可互换。ought to的反意疑问句用shouldn’t替代。
1. 表主语的义务或责任：
You should take care of your sister．
2. 指出一个正确、明智的动作：
They shouldn't allow parking here；the street is too narrow． 这儿不该允许停车；马路太窄了.
ought to / should have done:过去应该做而未做, oughtn’t to/ shouldn’t have done:过去不该做但做了。

You should/ought to have made the decision a week ago.
I shouldn't have made such a foolish mistake.
注意
You ought to have helped him with his English, _____ ?
A. won’t you
B. ought not you
C. shouldn’t you
D. wouldn’t you
My mother cooked a lot
of food for me. She has
been cooking all the morning.
She must be tired now.
Don’t tell anybody what I said. You ______ keep it a secret.
must
She called me yesterday evening
but I didn’t hear it.
I _________________ (be) asleep.
must have been
In China many children ________ wear uniform when they go to school.
have to
Last night Paul became ill suddenly.
We ________ call the doctor.
had to
2. must和have to
must的用法?
1）表主观义务、必要:? 主要用于肯定句和疑问句；
由must 引起的疑问句，
肯定回答:“必须,得,要”用must或have?to,?
否定回答: “不必”, 用needn’t或don’t?have?to.
mustn’t:禁止，“不能，不许”
注意
have?to?的用法?
1）must:主观, have?to:客观需要，不得不。??
Mother is out, so I have to look after the shop.
2）have?to?的否定形式：don’t have to=needn’t。
They don’t have to buy a computer at present. 　
【考例】─What do you think we can do for our aged parents?
─You____ do anything except to be with them and be yourself. (重庆 2007)
A. don’t have to B. oughtn’t to
C. mustn’t D. can’t
Must they do…? Yes, they must.
No, they needn’t/don’t have to.　　　　
比较must & have to
must have to
主观／客观 　 主观 　 客观
时态 现在，将来 　 多种
表推测 　　√ 　　×
询问意愿 　　√ 　　×
否定意 禁止，不允许 不必
【考例】The boss has given everyone a special holiday, so we ____ go to work tomorrow. (上海 2007春)
A. can’t B. mustn’t
C. needn’t D. shouldn’t
---Need I do the shopping now?
---Yes, you must./ No, you needn’t
I can manage the shopping alone. You _________ come with me.
needn’t
needn’t 对其它情态动词的回答:

--Shall I tell John about it?
--No, you __________.


--Must we do it now?
--No, you __________.

needn’t
(don’t have to)
needn’t
(don’t have to)
Could I borrow your dictionary?(委婉)
---- Yes，you can/may.
Sure. Go ahead.
Please yourself.
May I take this seat?(第一人称疑问句)
Yes, you may. No, you mustn’t.
The old restaurant
______ be very good.
It’s always full of
people.
The new restaurant
______ be very good.
It’s always empty.
must
can’t
Where is Bob?
Perhaps he is in his office.
=He ____ be in his office.
may
Perhaps she was ill yesterday.
=She _______ be ill yesterday.
might
1. ---Did the train arrive in time?
----No. It _______ two hours ago.
A. must have arrived B. ought to have arrived C. must arrive D. ought to arrive
B
情态动词考题:
2. “Must I drive to his house and pick up the children?” “No, ______ .” A. you shouldn’t B. you might not C. you needn't ? D. you mustn't
C
3. You ____ such a long composition. The teacher only asked for 300 words. You have written 600.
A. mustn’t have written
B. couldn’t have written
C. needn’t have written
D. do not have to write
C
3. We didn’t see Tom at the meeting yesterday.
He _____ it. A. mustn't have attended?
B. cannot have attended C. needn't have attended?
D. would have not attended
B
4. There is someone knocking at the door. ___ it be Tom? A. Can? B. Must C. Should? D. Ought to
5. Two years ago, my husband bought me a bicycle.
If you live in town, it is often faster than a car and you ___ worry about parking.
?? A. must not?? B. may not??
C. should not?? D. don't have to
A
D