人教新课标必修三 Unit 2 Healthy eating情态动词讲解

1、Unit 1Unit 1 Festivals around the world Grammar情态动词（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，情态动词表示说话人对某一动作或状态的态度，认为认为“可能可能”、“应当应当”、“必要必要”等等。但本等等。但本身词义不完全，不能单独作谓语动词，必须和不身词义不完全，不能单独作谓语动词，必须和不带带to的不定式（即动词原形）连用。情态动词没的不定式（即动词原形）连用。情态动词没有人称和书的变化。有人称和书的变化。can and could may and mightwill and wouldshall and sh

2、ouldmust and cant can and couldSo he can carry heavy books.ability He couldnt open the door by himself. abilityCould you open the door, please? requestCan/could的用法。的用法。1.意为意为“能够、会能够、会”，表示体力或脑力等方面的能力。，表示体力或脑力等方面的能力。2.意为意为“可以可以”表示许可，常在口语中代替表示许可，常在口语中代替may.3.意为意为“可能可能”用在肯定陈述句中表可能性，用在否定句或疑问用在肯定陈述句中表可能性，

3、用在否定句或疑问 句中表示猜测、惊讶等。句中表示猜测、惊讶等。4.can have done 用于对过去动作的推测，表可能，常用于否定句和用于对过去动作的推测，表可能，常用于否定句和疑问句中。疑问句中。e.g. I can speak English. Can I keep the book for a few days ? You cant be serious.（你不会是当真吧）（你不会是当真吧） She is two hours late .What can have happened?Can 和和 be able to 的区别的区别1.can 和和 could 表示能力时，有时可以用表

4、示能力时，有时可以用be able to 替换，由于替换，由于 只能表示现在时和一般过去时，当我们需要用现在完成时只能表示现在时和一般过去时，当我们需要用现在完成时 或其他时态时，就可以用或其他时态时，就可以用be able to表示。表示。当我们要强调过去确实使用了某种能力时，要用当我们要强调过去确实使用了某种能力时，要用was(were)able to,而不用而不用could。was able to表示表示“设设法干成某事法干成某事”而而 could只表示只表示“具备某种能力具备某种能力”。e.g. He is such a good swimmer that he was able to

5、 save the boys from drowning the other day.Could的用法的用法1。在过去的语境中，表示过去的能力、许可、可能。在过去的语境中，表示过去的能力、许可、可能。2。若不是出现在过去的语境中，它就是表达委婉口。若不是出现在过去的语境中，它就是表达委婉口气。气。could have done 表示对过去发生事情的推测。表示对过去发生事情的推测。e.g.I couldnt speak English two years ago. Where could she have gone?may and mightHe may be in his office.=(

6、perhaps he is in his office.)He might be having lunch.=( perhaps he is having lunch.)may and might1 1） 表示可能性（表示可能性（possibilitypossibility）, ,用于对用于对现在，过去或将来的推测，暗示不确定。现在，过去或将来的推测，暗示不确定。might might 不是不是maymay的过去式，它所表示的可能的过去式，它所表示的可能性比性比may may 小，含较多的怀疑。小，含较多的怀疑。He may be very busy now. ( (可能性较大可能性较大) )

7、He might be very busy now. ( (可能性较小可能性较小) ) may and might2 2） 表示许可（表示许可（permissionpermission），表示允许），表示允许别人做某事，别人做某事， 也可征求对方的许可。也可征求对方的许可。He may go now.We may keep the book for two weeks.3 3） 用于祈使句，表示祝愿。用于祈使句，表示祝愿。May you succeed!May you have a nice trip! may, might, can, could1. They (can/might) _be

8、 away for the weekend but Im not sure.2. You (may/might) _leave now if you wish.3. (could/may) _you open the window a bit, please?4. He (can/could) _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表示猜测表示猜测may表示许可表

9、示许可could表示请求表示请求could表示猜测表示猜测can 表示能力表示能力may not表示不允许表示不允许may, might, can, could7. They (can not/may not) _ still be out, the light is on in the house.8. You (couldnt/might not) _ smoke on the bus.9. With luck, tomorrow (can/could) _be a cooler day.10. You (can/might) _ be right, but Im going back t

10、o check it.表示许可表示许可couldntcould表示猜测表示猜测can not表示猜测表示猜测(不可能不可能)might表示猜测表示猜测will and would 1 1）表示意愿）表示意愿 表示愿意做或主动提出做，如意志表示愿意做或主动提出做，如意志, ,愿望或决心愿望或决心That bag looks heavy, Ill help you with it.( offering to do sth)- You know that book I lent you. Can I have it back if youve finished with it?- Of course

11、. Ill give it to you this afternoon. (agreement)Thanks for lending me the money, Ill pay you back on Friday. (promise) will and would2 2）表示习惯）表示习惯(habit, custom)(habit, custom)This old man is strange. He will sit for hours without saying anything. We would sit around Grandpa after supper, listening

12、to his stories.3 3）表示请求（）表示请求（requestrequest）, , 用于第二人称用于第二人称, , would would 比比will will 更委婉。更委婉。 例如：例如：Will you come this way, please?Would you open the window? shall and should1）shall 的用法的用法a.shall a.shall 在疑问句中用于第一，第三人称，表示征在疑问句中用于第一，第三人称，表示征求对方的意见。求对方的意见。Shall we put off the sports meeting until

13、next month?Shall Tom go there with me tomorrow? b.shall b.shall 用于第二，第三人称，表示说话人给对方用于第二，第三人称，表示说话人给对方的命令，警告，允诺或威胁。的命令，警告，允诺或威胁。You shall fail if you dont work harder. （警告）（警告）He shall have the book when I finish reading it. (允诺允诺)He shall be punished. (威胁威胁) shall and should2) should 的用法的用法a. should

14、a. should 表示劝告、建议、命令。表示劝告、建议、命令。You should go to class right away.b. should b. should 表示期待，用于表达合理推断表示期待，用于表达合理推断(prediction(prediction，意为，意为“应该应该” )” )，或明显的结果（意，或明显的结果（意为为“可能可能”）且所期待的事几乎是事实。）且所期待的事几乎是事实。It is three oclock, the football game should begin now. Mary took dancing lessons for years, so s

15、he should be an excellent dancer. 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_

16、. 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 dont you try on this dress? It _ look nice on you.will, would, shall, should, must:mustntshouldwouldwillmustmustshouldwill表示禁止表示禁止,不许可不许可表示建议表示建议,命令命令表示过去习惯表

17、示过去习惯表示意愿表示意愿表示必须表示必须表示肯定猜测表示肯定猜测表示建议表示建议表示将会表示将会,一定会一定会must and cantmust 用来表示用来表示“命令命令”、“推测推测”等含义。等含义。 1 1）表示规定、指令）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，常常翻译为译为“应该、必须应该、必须”之类意思。之类意思。mustntmustnt表示禁止表示禁止You must have a passport if you want to go abroad. 2) 2) 表示主观的命令、禁止表示主观的命令、禁止

18、表示主观的命令、禁止时，主要指说话者主观的命令或强烈表示主观的命令、禁止时，主要指说话者主观的命令或强烈的劝告。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 neednt. 。must and cant3）表示猜测，语气非常肯定，近乎确定的意味，）表示猜测，语气非常肯定，近乎确定的意味，一般用于肯定句，意为肯定一般用于肯定句，意为肯定。其否定为。其否定为cant， 意为不可能意为不可能. 。You

19、 must be ill. I can see it from your face.He cant be at home. I saw him in the classroom just now. must and have to1.must1.must用于一般问句中用于一般问句中, ,肯定回答用肯定回答用mustmust否定式否定式用用 needntneednt或或dont have todont have to，做，做 “不不必必”,mustnt”,mustnt表示表示“禁止，不允许禁止，不允许” Must I finish all assignments at a time? Yes,

20、you must. No, you neednt. 2.2.表示表示“必须必须”这个意思时，这个意思时，mustmust 和和havehave toto 稍稍有区别。有区别。mustmust着重说明主观看法，着重说明主观看法，havehave toto 强调客强调客观需要。另外，观需要。另外，havehave toto 能用于更多时态。能用于更多时态。I dont like this TV set. We must buy a new one. There was no more bus. They had to walk home.Not sure Very sure He might be

21、 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情态动词的猜测用法1.-There were already five people in the car but they managed to take me as well. -It _a comfortable journey. ( ) A. cant be B. mustnt have been

22、C. shouldnt be D. couldnt have beenD2.The fire spread through the hotel very quickly but everyone _ get out. ( ) A. had to B. would C. could D. was able toD3. Peter _ come with us tonight, but he isnt very sure. A.must B. can C. may D. willC4. - Could I call you by your first name? - Yes, you_. A. will B. could C. may D. mightC5. Sorry, I m late. I _ have turned off the alarm clock and gone back to sleep again. A.might B. should C. can D. willA6.-Excuse me, but I want to use your computer to type a report.-Yo