高中英语Unit 4 Exploring literature多媒体教学课件ppt

情态动词

情态动词作为谓语的一部分，无人称和数的变化(have to除外)；一般不能单独使用，要与谓语动词构成完整谓语，但在回答时，可单独使用。情态动词有can(could)，may(might)，must，have to，shall(should)，will(would)，dare(dared)，need(needed)，ought to等。

[观察思考]

①Today，both male and female athletes from around the world can take part.

②I am sure all Chinese must have felt proud when Xu Haifeng won the first gold medal for his country.

③Naturally，after I tell her what to do，my daughter must do the opposite!

④You should apologize to Mary for your rude remarks.

⑤Mr.Green must be a teacher，isn't he?

⑥He may come here by train，but I am not sure.

⑦Need I pay the whole amount now?

⑧There has to be a reason for his strange behaviour.

[归纳用法]

1．can(could)

(1)表示能力，can表示现在的能力，could主要指过去的能力。

You can tell the significance of climate change to us.

你可以告诉我们气候变化的重要意义。

[名师点津]　can表示能力的时候，还可以用be able to代替，can用于一般现在时，could用于一般过去时。can(could)表示具备这样的能力，但不一定做了；而be able to表示不但具备这样的能力，而且经过努力做了。

Can you come to the party tomorrow?

明天你能来参加聚会吗？

He was a good swimmer so he was able to swim to the riverbank when the boat sank.

他是一个很擅长游泳的人，所以当船下沉时，他能够游到河岸上。

(2)表示请求许可。

当请求允许做某事时，两者均可用，但用could语气更委婉。当表示允许某人做某事时，一般要用can，而不用could。

—Can/Could I use your bike tomorrow morning?

—Yes，you can./No.I'm afraid not.

——我明天早晨能用你的自行车吗？

——是的，可以。/不，恐怕不行。

(3)表示推测。

can表推测时一般用于否定句和疑问句中(could一般无此限制)。表示对过去发生的行为怀疑或不肯定时，常用“can/could＋have＋过去分词”的否定或疑问形式。

It can't/couldn't be true.

那不可能是真的。

We could go there this summer.

今年夏天我们可能要去那里。

(4)表示客观的可能性(并非主观推测)，意思是“有时候可能会”。

The weather in Shanghai can/could be very cold in winter.

上海冬季可能很冷。

(5)表示惊异、怀疑，不相信的态度(主要用在否定句、疑问句或感叹句中)。

How can you be so careless!

你怎么那么粗心呀！

[即学即练1]　选词填空：can，could，be able to

①Man can not live without air.

②Being a wise person，he finally was able to find the place.

③The cheater said that he could turn stone into gold.

2．may(might)

(1)表示允许，might可以指过去，也可指现在，语气更委婉。

May (Might) I ask for a photo of your baby?

我可以要一张你宝宝的照片吗？

[名师点津]　对may的一般疑问句的肯定回答可用may或can，但作否定回答时要用mustn't或can't。

—May I smoke here?

—No，you mustn't./You'd better not.

——我可以在这里吸烟吗？

——不，不可以。/你最好不要吸烟。

(2)表示可能。可以指过去，也可以指现在，但语气不肯定。

She may not know about it.

她可能不知道这件事。

(3)用于表祝愿的句子中。

May both the bride and groom be happy!

祝新娘新郎幸福！

3．must(have to)

(1)must表示必须，没有时态变化。强调的是一种主观看法，也表示责任或义务。have to表示“必须，不得不”，是由于某种外界(客观)原因而“必须，不得不”做某事，也可表示经常的或习惯性的事“必须”做。mustn't表示禁止做某事；have to的否定形式为don't/doesn't/didn't have to表示“不必”。have to可用于多种时态中。

My brother was very ill，so I had to call the doctor at midnight.

我弟弟病得很厉害，我必须半夜里把医生请来。(客观上需要做这件事)

He said that he must work hard.

他说他必须努力工作。(主观上要做这件事)

[名师点津]　回答must引出的疑问句时，如果是否定的回答，不能用mustn't，而要用needn't或don't have to。

—Must we hand in our exercise books now?

—Yes，you must.(No，you needn't./No，you don't have to.)

——我们现在就必须要交练习本吗？

——是的，必须。(不，不必。)

(2)must表示猜测。意为“想必，准是，一定”等，只用于肯定句。

She's wearing a diamond necklace.She must have a lot of money.

她戴着钻石项链，一定很有钱。

(3)must还可表示“偏要”。表示说话人不耐烦、不满的情绪。

Why must it rain on Sunday?

为什么偏要在星期天下雨？

[即学即练2]　用适当的情态动词填空

①My sister is ill，my mother has to look after her.

②There's a lot of noise from next door.They must be having a party.

③—Must I return all the books in three days?

—Yes，you must．(No，you needn't/don't have to．)

④If you must go，at least wait until the storm is over.

4．shall

(1)表示征求意见，用于第一、第三人称疑问句。

Shall I get you some more tea?

再来点茶好吗？

(2)表示说话人的意愿，有“命令、允诺、警告、决心”等意思，用于第二、第三人称陈述句。

You shall come on time.

你必须准时到。(命令)

He shall have the book when I finish reading it.

我读完这本书就给他。(允诺)

Nothing shall stop us from carrying out this plan.

没有什么事情能阻止我们实施这项计划。(决心)

(3)shall用于第三人称，表示按照法律、条文或规定必须做的事，意为“应，必须”。

No reader shall remove a book from the library without permission.

未经许可，读者不准把书带出图书馆。

[即学即练3]　选择下列句中shall的含义

A．允诺　B．警告　C．威胁　D．征求意见

①You shall fail if you don't work harder.B

②You shall get an answer from me tomorrow.A

③You shall be punished for what you've done.C

④Shall I watch TV for a while？D

5．should

(1)表示义务、责任。意为“应该”(某件事宜做)，用于各种人称。

You should be polite to your teachers.

你对老师应该有礼貌。

(2)表示可能性很大的猜测，意为“想必一定，照说应该，估计”等。

The film should be very good as it is starring first­class actors.

这部电影是一流演员主演的，估计拍得很好。

(3)表示说话人的惊讶、愤怒、失望等特殊情感，意为“居然，竟然”。

Amazing！You should wear slippers at work.

真令人惊讶，你竟然穿着拖鞋上班。

6．will(would)

(1)表示意志或意愿。will指现在，would指过去，用于否定句表示“不肯，不乐意”。

I will never do that again.

我决不会再做那种事了。

(2)表示征求意见或提出请求。主要用于第二人称疑问句中，will和would均可用，would此时不表示过去，而是表示委婉语气。

Will/Would you pass me the book please?

请你把书递给我好吗？

(3)will和would可分别表示现在和过去反复发生的动作或某种倾向，意为“总是；常常”。

He will sit up there all night.

他总是整夜坐在那儿。

I said I would do my best.

我表示过要尽最大努力。

[明辨异同]　used to，would

[即学即练4]　用适当的情态动词填空

①Will/Would you please save some dessert for me?

②He used to be a very strong man，but now he isn't.

③We would sit in the yard every evening and listen to his stories when we were young.

7．ought to

(1)表示职责和义务，意为“应该”(因责任、义务等该做)，口气比should稍重。

You oughtn't to smoke so much.

你不应该抽这么多烟。

(2)表示推测，暗含很大的可能性，类似于should。

Han Mei ought to know his telephone number.

韩梅应该知道他的电话号码。

8．need和dare

(1)它们作情态动词时，后跟动词原形，常用于否定句、疑问句中。一般不用于肯定句，无第三人称单数形式。dare有过去式形式，构成疑问句时，将其移至句首；构成否定句时，直接在其后加not。

—Need I tell him everything?

—Yes，you must./No，you needn't.

——我要告诉他一切吗？

——是的，必须。/不，没有必要。

How dare she do things like that to me?

她怎么敢对我做那样的事呢？

(2)作实义动词时，其否定和疑问的构成需借助do/did/does，need后面接带to的不定式，而在疑问句和否定句中，dare后可省去to。有人称和数的变化。

He didn't dare(to)go there.

他不敢去那儿。

Right now you need to stay still until help comes.

现在你需要待着别动，直到有人来帮忙。

[即学即练5]　用dare/need的适当形式填空

①You needn't hurry.There is still enough time to go.

②—Must I go right now?

—No，you needn't．

③How dare you say I'm unfair?

④He daren't speak English before such a crowd，dare he?

⑤He needs to finish it this evening.

⑥Don't you dare touch it?

9．情态动词表示推测或判断的用法

下表是表示推测的情态动词使用的场合：

情态动词＋have done的用法

(1)should/ought to have done表示“本来应该做某事而实际上未做”，而shouldn't/ought not to have done则表示“本不应该做某事而实际上做了”。

You should/ought to have told me about it earlier.

关于这件事你本应该早点告诉我的。

You shouldn't/ought not to have said such words to your parents.

你本不应该给你父母说这样的话。

(2)needn't have done表示“本无必要做某事而实际上做了”。

You needn't have walked so quickly since time was enough.

你本来不必走这么快的，时间很充足。

(3)could have done表示“本来可以做某事而事实上未做到”。

I could have come on time，but my car broke down on the way.

我本来可以准时到的，但是我的车在路上坏了。

(4)may/might have done表示“可能发生过某事”或“本来也许可以做某事(实际上没做)”。

You might have given him more help，but you were so busy.

你也许可以给他提供更多帮助的，但你太忙了。

[即学即练6]　补全句子

①I could have helped you(我本来可以帮助你的)，but I was too busy then.

②You must have gone to bed late(一定是睡得很晚) last night.Your eyes are red.

③You know the story very well.You may/might have read it(可能读过它) before.

Ⅰ.单句语法填空

1．It is strange that such a famous poet should be so rude to a lady.

2．You must come here on time，or you'll be fined next time.

3．I needn't have cooked so much food.Nobody was hungry.

4．He told me he would be free tonight.

5．I may/might finish reading the novel tomorrow，but I am not sure about it.

6．You ought to have given him some advice.He was too upset at that time.

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

8．She was so frightened that she didn't dare (to)breathe(breathe) a word of it to anyone else.

9．He finished all the work himself; in fact, he could have asked his friends for help.

10．You may feel all the training a waste of time，but I'm a hundred percent sure later you'll be grateful you did it.

Ⅱ.短文语法填空

Lucy is an outgoing lady.She 1.can play many kinds of musical instruments.Actually，she 2.could play the piano when she was 8 years old.Lucy also keeps taking exercise every day.She says that she has to do some sports because she 3.must keep slim.“You 4.shall get fat soon if you don't take exercise every day.” She usually says to her friends.

As for her，an elegant lady should try to keep fit.However，last week，she found that she 5.might put on weight and her husband suggested that she 6.should lose weight. However，she is always lacking in time because she has to take care of her children.

One night after supper，she walked quickly to go dancing at the park.On her way，she thought that the dancing must 7.have begun (begin) and the coach 8.could have taught many new moves, but the coach was absent that night, so she was regretful.