发布时间 : 星期五 文章必修3 Unit 2 Healthy eating 情态动词(2)更新完毕开始阅读79ca571bcc17552707220856
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高一 林静 学 科 英语 版 本 人教实验版 必修3 Unit2 Healthy eating：情态动词（2） 【本讲教育信息】
一、教学内容
必修3 Unit 2 Modal verbs (2) 情态动词（2）
ought to / ought not to /have to / don‘t have to / mustn‘t /need/needn‘t / 情态动词+ have done
二、知识精讲
（一）ought to／ought not to
ought to意为“应该，应当”，是情态动词，没有人称和时态的变化，与should同义，语气较强。
例：
You ought to obey your parents.你应该听父母的话。 You oughtn‘t／ought not to blame him.你不应该责备他。 —Ought I to go? 我该去吗? —Yes，you ought to. 是的，你应该（去）。 1. 表示职责和义务
She ought to look after her children better. 她应该把自己的孩子照顾得好一些。 Humans ought to stop polluting nature. 人类应该停止污染大自然。 2. 表示建议和劝告
We really ought to buy a car, oughtn‘t /shouldn‘t we? 我们真该买辆车了，是吗？ You ought to obey your parents. 你应该听父母的话。 3. 表示猜测，可能性较大
He ought to be here soon – he left home early. 他应该快到了——他很早就出门了。
The seats ought to be enough for all the guests. 这些座位应该够所有客人使用了。 知识拓展
辨析：ought to/should
一般说来，两者可互换，只是ought to语气略强。另外，表示出于法令规则、行为规则、道德责任等客观情况而“应该”做某事时，一般应用ought to；若用should则含有个人意见，强调主观看法。
We ought to(should)go and see our teacher sometime. 我们应该抽时间去看望我们的老师。
They ought to go and see Mary tomorrow，but I don‘t think they will.
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按理他们明天应去看玛丽，但是我认为他们不会去的。
（二）have to／don‘t have to／mustn‘t
（1）have to 表示客观上的必要性，强调在客观条件下必须去做某事，意为“不得不，必须”。在口语中常用have got to 代替。
She has to earn her living. 她不得不自食其力。
You have got to go across the busy market to go to the station. 去车站你不得不穿越拥挤的市场。
(2) have to的否定式是don‘t have to，表示没有义务或必要做某事，意为“不必”，常可以回答由must提问的疑问句。而must的否定式mustn‘t主要指说话人主观的命令或强烈的劝告。
—Must we hand in our homework this afternoon? 我们必须今天下午交作业吗?
—No, you don‘t have to.(No. you needn‘t) 不，不必。
You mustn‘t tell him the secret. 你不能告诉他这个秘密。 知识拓展
辨析have to / must
have to与must都是表示“必须”，但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。
（三）need／needn‘t
need“需要，必要”，既可作情态动词，也可作实义动词
用作情态动词，后接动词原形，没有人称和数的变化，通常用于否定句和疑问句中。
There‘s plenty of time. We needn‘t drive so fast. 时间很充足，我们不必开这么快。
—Need I tell him everything that happened to his parents? —我有必要告诉他有关他父母发生的一切吗？
— Yes, you must. / No, you needn‘t. —是的。/不，没必要。
（1）用作实义动词，有动词的各种形式变化，可用于一切句式；构成否定句和疑问句时要借助于助动词do或does
例如：
You need to be careful.你得小心些。
We didn‘t need to tell him the truth. 我们不需要告诉他真相。
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Do I need to say my telephone number again? 我需要再说一遍我的电话号码吗？ 知识拓展
（1）need作实义动词表示主语“需要被??时”，后面可以接不定式的被动语态或动名词的主动语态表示被动含义。
These trees need to be watered. = These trees need watering. 这些树需要浇水。
(2) dare既可作情态动词，也可作实义动词.
He dared say what he thought. = He dared to say what he thought. 他敢于说出自己的想法。
I didn‘t dare to go back to take a look. = I dared not go back to take a look. 我不敢返回去看一眼。
How dare you speak ill of others? = How do you dare to speak ill of others? 你怎么敢说别人的坏话？
（四）英语中其它情态动词的用法。 1. used to do “过去常常” I used to go to the cinema a lot but I never get the time now. 我过去常常看电影，而现在总是没有时间。
He didn‘t use to / usedn‘t to go swimming but now he does. 他过去不常去游泳，但现在常去。
What did the boy use to think of his mother before the day she cried? = What used the boy to think …?
在男孩看到妈妈哭的那天以前他是怎样看待他母亲的？ 2. had better… “最好??”
You‘d better leave now or you will miss the bus. 你最好现在就走， 不然就赶不上公共汽车了。 3. would rather/sooner … “宁愿??” He would rather keep time for his hobbies. 他宁愿把时间花在自己的业余爱好上。
I would rather stay here than go home. 我宁愿待在这也不愿回家。 即学即用：
① The girl used to be very interested in music，________ she?
A. didn‘t B. use C. used D. usedn‘t to
② John spent the weekend in the country as he ________ into the office on Saturday. A. needn‘t have gone B. mustn‘t go
C. didn‘t have to go D. shouldn‘t have gone ③ You ___hand it in at once, you may hand it in tomorrow. A. needn‘t B. may not C. can‘t ④ —-Shall we go skating or stay at home? —-Which ___ do? A. do you rather C. will you rather
D. must not
B. would you rather D. should you rather
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⑤ I ________ tell you what he did for fear that he should be angry with me. A. daren‘t B. daren‘t to C. dared not to D. dares not ⑥ Jack‘s ill, so they ______ change their plans. A. must B. should C. have got to ⑦ —Lucy doesn‘t mind lending you her dictionary. —She ______. I‘ve already borrowed one.
D. ought to
A. can‘t B. mustn‘t C. needn‘t D. shouldn‘t ⑧ They are having classes. You ______make such noise here.
A. don‘t have to B. ought not to C. needn‘t D. have got to ⑨ You ________ tell anybody else about it; this is a secret between us. A. don‘t B. needn‘t C. mustn‘t D. won‘t ⑩ Must I get through the business in one evening? No, you ________. A. mustn‘t
B. haven‘t
C. needn‘t to D. don‘t have to
（五）情态动词+have +过去分词的用法 1. 表示推测或估计
（1）may / might have done “大概已经”，通常用于肯定句和否定句中。
It is eight o‘clock .They may have arrived. 现在是8点钟。他们可能已经到了。 He looks very happy. He might not have known the result. 他看上去很高兴。他也许还不知道结果。
（2）can/ could have done “可能已经”，通常用于疑问句和否定句中。 She didn‘t come to school yesterday. Can she have been ill? 她昨天没来学校，难道她生病了？
Mike can‘t have found his car, for he came to work by bus this morning. 迈克一定还没有找回他的车，因为今天早上他是坐公共汽车来上班的。 （3）must have done “肯定已经”，只用于肯定句中。 It must have rained last night, for the streets are wet. 昨晚肯定下雨了，因为街道是湿的。 （4）should have done “应该已经”，可能性较小。 They left here early and should have arrived by now. 他们一早就离开了这里，现在应该到了。 2. 表示遗憾或责备
（1）might have done 通常用于肯定句中，表示“本可以”，含有轻微的责备口吻或遗憾语气。
You might have helped your classmate out of his difficulty. 你本可以帮助你的同学解决困难的。
（2）could have done 通常用于肯定句中，表示对过去能做而未做的事感到惋惜、遗憾。 The driver could have avoided the accident. 司机完全能够避免这次车祸的。
（3）should have done =ought to have done 可用于肯定句和否定句中，表示该做而实际未做（不该做而实际做了）的事，含有责备的意味。
It is too late. You should / ought to have prevented him from going there. 现在太迟了，你当时就该阻止他去那儿的。
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