情态动词讲解与练习.ppt

1、What can you see in the picure?,Read,If you want to cross a street, you must wait for the green light. You mustnt cross in front of the traffic. If the light is yellow, you should wait. If you are not careful, a car may hit you. If you are in the UK, you have to drive on the left.,and find out,Modal

2、 Verbs,情态动词,1. 情态动词有一定的意义、不能独立使用，它和后面的动词构成谓语。 2. 除have to外，没有人称和数的变化，即情态动词第三人称单数不加-s。 3. 除have to外，情态动词还兼有助动词的作用。 4. 情态动词除ought to和haveto外，后面只能接动词原形 5. 情态动词没有非谓语形式，即没有不定式，分词等形式。,只作情态动词的 can/could, may/might, ought to, must,可情态可实义的 need, dare,可情态可助动词的shall/should, will/would,相当于情态动词的have to,情态动词的语法特征

3、,can (could),Some of us can use the computer now, but we couldnt ten years ago. Can/Could I borrow these books? The story can not be true.,1）能，会：表示能力 2）可以，表示请求和允许，(may较正式，could较委婉） 3）可能，表示推测，只用于否定句和疑问句中,注意：could也可表示请求，语气委婉，主要用于疑问句，不可用于肯定句，答语应用can（即could不能用于现在时态的简略答语中）。如： Could I come to see you tomo

4、rrow? Yes, you _. （否定答语可用No, Im afraid not.,can,can表示能力时，还可用be able to代替，但Can只有一般现在时和一般过去式；而be able to则有更多的时态。如 Ill not be able to come this afternoon. 当表示“经过努力才得以做成功某事”时应用be able to，不能用Can。如： He was able to go to the party yesterday evening in spite of the heavy rain.,may (might),1. -May I watch TV

5、 after supper? - Yes, you may. / Certainly./Sure./Of course. - No, You cant. / Youd better not. No, you mustnt. 2. He may be busy now. 3.May you succeed！,可以，表示请求和允许,相当于can (注意一般疑问句的回答） 2) 可能，或许，表示推测，疑问句不用于此含意 3) 在祈使句中，表示祝愿,注意： 表示请求、允许时，might比may的语气更委婉一些，回答其引导的一般疑问句时，跟may引导的一般疑问句的回答一样。如：, Might I use

6、 your pen? No, you cant/ you mustnt./youd better not. yes，you may./please/certainly. 用May I . 征询对方许可在文体上比较正式，在口气上比较客气。在日常口语中，用Can I . 征询对方意见在现代口语中更为常见。,must,If you want to cross a street, you must wait for the green light. You mustnt cross in front of the traffic. - Must I be home before 8 oclock? -

7、 Yes, you must. - No, you neednt / dont have to. 3. There must be something wrong with my computer.,must: 必须；mustnt: 不准，禁止 回答带有must的问句时，否定式常用neednt 或dont have to. 3) 一定,表示肯定的猜测.（疑问句否定句不用于此含义）,have to,If you are in the UK, you have to drive on the left. The animals we eat have to spend their lives li

8、ving in tiny spaces.,have to (客观上)不得不,I have to be at work at nine oclock every day. She has to work on Saturdays. Theyll have to stay in a hotel. Does Dick have to go to Beijing on business? He didnt have to go there last week.,have to + 动词原形,have to 有人称、数、时态的变化 当主语为第三人称单数时，用has to + 动词原形,变问句或否定句时，

9、需借助助动词。,not have to = neednt,I have to be at work at nine oclock every day. She has to work on Saturdays. Theyll have to stay in a hotel. Does Dick have to go to Beijing on business? He didnt have to go there last week.,must 和have to,两者都表示必须 must 侧重于说话者的主观看法，认为有必要或有义务去做某事； have to 则重于表示外界客观需要，含有不得不或

10、被迫之意,Ididnttaketheraincoatwithmeyesterday. I_ waitformyfather. A. havetoB. hastoC. hadtoD. must 2. Jacks ill, so they _ change their plans. A. must B. should C. have to D. ought to,need,1need作情态动词无人称或数的变化，后接动词原形，多用于否定句和疑问句中。 如：Youneedntworry.你不必担心 I neednt have brought the raincoat with me in such a

11、 sunny day yesterday.,2由need引出的一般疑问句，肯定回答常用must或haveto;否定答语常用neednt.如：,NeedIanswerthequestion?我需要回答那个问题吗？ Yes,youmust.-Yes,youhaveto.是的，你必须回答。 -No,youneednt./you dont have to不，不必了。,Need 做行为动词,Need sth Need to do sth Need doing=need to be done表被动 否定： dont need to,need的用法,1. -Do we need _ for the tick

12、et to the park? - No, we neednt _ that. Its free. to pay, to do B. to pay, do C. pay, to do D. paying, doing 2. I dont need _ to school today. A. to go B. go C. going 3. Need he _? No. he _. A. to run, neednt. B. run, doesnt need. C. run, neednt 4. Will Sam _ tomorrow? A. need to leave B. need leave

13、 C. needs to leave,shall,shall 用于第一人称，征求对方的意见。 What shall we do this evening? shall I clean the room for you?,should,表示“应该”，常用来表示劝告、建议；认为“某人应该做某事”或“有义务责任做某事”。 We should obey traffic laws. You shouldnt watch TV every day。 You shouldnt have made this kind of silly mistakes. Tom should have brought his

14、 report today. 这时它可以和 ought to， be supposed to 互换使用,2) Should (ought to)表示推测时，是指有一定根据的推测，意为“可能、该”,-When can I come for the photos? I need them tomorrow, -They _ be ready by 12:00,will 和would,1)表示意志或意愿：决心，愿意， We will do our best to save the child. 我们会尽力抢救这个孩子。 I told her to stop crying, but she just

15、wouldnt listen. 我叫她别哭,可她就是不愿听。 I will never do that again. 我绝不会在做那件事了。,2)表示请求、建议或征求对方意见时，用Would you? 比用Will you?更委婉。如：,Will/Would you please keep the door open?请让门开着好吗？ Will/Would you go with me?你愿意和我一起去吗?,相关情态动词,would like表示意愿 I would like to have a word with you. 我想同你说句话。 would ratherthan宁愿也不愿 I w

16、ould rather fail than cheat in the examination. 我宁愿考不及格，也不愿意考试作弊。,情态动词命题角度,1.情态动词引导的一般疑问句的回答 2.情态动词用于推测 3.情态动词的含义,推测肯定句、否定句、疑问句 （4+4+2）,肯定句: 否定句: 疑问句:,可能不,不可能,一定,must/may/might/could,can/could/may/might+not,Can/Could?,这些词后接动词原形是对现在事情的推测，后接完成式则表示对过去事情的推测；其中can，may/might，must有时还可接进行时表示对现在正在进行的事情的推测。,他

17、有可能去武汉了吗？ 这时候他会在做什么？ 她不可能在说谎。 你妈妈可能正等着你回家呢。 他们肯定在离我们不远处尾随着我们。,Can he have gone to Wuhan?,What can he be doing at this moment?,She cant be telling a lie.,Your mother may be waiting for you to return home.,They must be following us just a little behind us.,推测基础用法show,1. I dont know where she is, she m

18、ay be in Wuhan. 2. -Is John coming by train? -He should, but he may not. He likes driving his car. 3.Can he be at home now? 4.He cant be at home. He has gone to Beijing. 5.He must be at his office, for its time for work.,Summary,can/could 1）能，会：表示能力 2）可以，表示许可 3）可能，表示推测,may /might 1) 可以，表示许可 2) 可能，或许

19、，表示推测,must must: 必须；mustnt: 不准，禁止 回答带有must的问句时，否定式常用neednt 或dont have to. 3) 一定，表示肯定的猜测。 （否定猜测用cant）,have to 则重于表示外界客观需要，含有不得不或被迫之意,need 1) 作情态动词 2) 作行为动词（有人称和数变化，后接名词/带to的动词不定式）,Summary,注意回答形式： 1) May I? Yes, you may. No, you cant (mustnt). 2) Must I ? Yes, you must. No, you neednt.you dont have to

20、 3)Need i.? Yes, you must/have to. No, you neednt.you dont have to 4)Could you.? Yes，I can./Sure./Certainly. 否定:Sorry,I am afraid not. 5)Might I.? - Yes, you may. / Certainly./Sure./Of course. - No, You cant. / Youd better not.,Exercises: Can you lend me your MP3? Sorry, I _. My father has taken it

21、with him. A. mustnt B. cant C. neednt D. shouldnt 2. Shall I go and meet you at the airport? No, thanks. I _ take a taxi home. A. need B. must C. should D. can 3. I cant find Dad. Where is he? Im not sure. He _ be in the study. A. must B. may C. need D. will 4. All the passengers _ wear seat belts o

22、n the plane. A. can B. may C. will D. must,Exercises: 5. _ the exam paper be handed in right now? No, it doesnt have to. You may hand it in before 11:30. A. Can B. Must C. Should D. May 6. Must we get to the station before 6:00 ? No, you _. The train leaves at 9:00. A. mustnt B. neednt C. wont D. cant 7. Mary, _ you speak Chinese? Yes, only a little. A. must B. need C. may D. can 8. _ I come in ? Sure, come in, please. A. Will B. May C. Must D. Need,Exercises: 9. _ I use your mobile phone? Certainly. Here you are. A. May B. Must C. Should D. Need May I put my b