情态动词和虚拟语气

1、情态动词和虚拟语气备课者：丁杰常考点清单 情态动词的类型和特征情态动词的类型一、 情态动词有：must, cancould,may(might),ought to, had better, shall(should),will(would),have(has) to, used to, need, dare二、 情态动词的特点1.有一定的词义,但不能单独作谓语,他们要和行为动词或连系动词连用,构成谓语，后面接动词原形.2.没有人称和数的变化（除了have to以外）.3.情态动词一般有时态变化（除must, ought to以外）.常考点清单二 情态动词用法要点一、 表能力（can, be a

2、ble to）1.can有两种时态：can/could2.be able to有更多的时态：was (were) able to/will be able to/have been able to.3.表示过去有能力并且成功地做了某事，要用was/were able to相当于succeeded in doing something./ manage to do sth. 而不能用could.二、 表推测（可能性）：can/could, may/might , must, should(ought to)1.can(could)常有于否定句和疑问句，may(might)常用于肯定句和否定句，m

3、ust, should(ought to)用于肯定句.2.在肯定句中，may表示“可能”，must表示“一定，准是”，在否定句中，cant 表示“不可能”，may not表示“可能不”. 比较：He must be in the classroom for I saw him just now. He cant be in the classroom now for I saw him play basketball on the playground. He may / might not be in the classroom, but I am not sure. 3.can 也可以用于

4、肯定句，但表示客观理论上的可能性;may用于肯定句中，表示具体理论上的可能性.结构：can/may/musthave done/be doing /do something Tigers can eat man. Accidents can happen on such rainy day. Everyone can make a mistake. The part of the country can be very warm in September. 4.must 表推测用于肯定句，否定句用cant/couldnt5.must have done/must do something/mu

5、st be doing something的反意疑问句与must 后面的动词保持一致. He must be kidding, isnt he? You must be kidding, arent you?He must have finished his homework, hasnt he? You must have finished your homework yesterday, didnt you? He must be helping the old man to water the flowers, _B_ ?(2009,陕西卷) A. is he B. isnt he C.

6、 must he D. mustnt he Hi, Tom. Any idea where Jane is? (2009,重庆卷) She _C_ in the classroom. I saw her there just now. A. shall be B. should have been C. must be D. might have been 6.must表示“偏要、硬要”做某事.How old are you, madam? If you must know, Im twice my sons age.If you must smoke, please go out. Must

7、 you make so much noise?你非得弄出这么大的声响吗？三、表示必要性 must/have to1.must 表“必须”,是主观上的认识. Must I clean all the room?Yes, you must.No, you neednt. /No, you dont have to.May I use your dictionary? Yes, you may. No, you mustnt. (委婉的拒绝可用：Sorry, but I am using it Now.或Youd better not.)2.have to 表“不得不”，是客观上的认识.dont

8、have to =dont need to do something =neednt do something四、 表示请求、允许、允诺1.shall 用于第一称或第三称的疑问句，用于征求对方意见. 结构是：shall I/we/he/ she / they Shall we go to the movie tonight? Shall the driver wait outside? 司机在外面等着可以吗？2.shall 用于陈述句中的二、三人称，表许诺，命令，警告，威胁等. You shall have this book tomorrow. You shall not have the

9、computer if you dont take good care of it.3.当宣布法律、法规的规定时，也要用shall.4.Could /Might I borrow your dictionary ? Yes, of course you can/may. No, Im afraid not.不可说：Yes, you could/might. 回答允许时，用could/might 表委婉是不恰当的.五、had better, should/ought to的用法这三者都可以用来提建议，语气强弱顺序：had better<should<ought toshould/ou

10、ght to的用法：1.常用来表示因为有责任、义务，而应该做某事. 如：You shouldnt leave a baby alone in the house. The students ought to obey the school rules.2.表示劝告或建议，“应当，宜于”.如：He should stop smoking.3.表猜测，“理应，按理说应该，总应该”.如：If he started at seven, he ought to /should be here now. Hows your tour around the North Lake? Is it beautif

11、ul?It should be, but it is now heavily polluted.When can I come for the photos? I need them tomorrow afternoon. They should be ready by 12:00.4.should还有“竟然，竟会”的意思，表“惊讶，愤怒”等情绪. Why/How+ should?表示“竟会，怎么会”. Why should you be so late today? How should I know?You cant imagine that a well-behaved gentlema

12、n should be so rude to a lady.六、would的用法： 1.过去将要 2.过去常常 3.表决心，决意，过去的意愿He promised the teacher that he would not smoke again.Why didnt you come to Simons party last night?I wanted to, but my mom simply C not let me out so late at night. A. could B. might C. would D. should 4.交际用语中表达请求，许可，语气客气，委婉. Wou

13、ld you do me a favor? 请帮我一下，好吗？七、will 的用法1.表意愿 Write to me when you get home. I will. I will help you. 2.现在或将来的习惯 The old man will sit by the window for hours. 3.临时作出的决定 I heard our teacher was ill. Well, I will see him this afternoon. Ann is in hospital. (2009，江苏卷) Oh, really? I D know. I _ go and

14、visit her. A. didnt; am going to B. dont; would C. dont; will D. didnt; will 4.表示必然的趋势 Fish will die without water. Human beings will not survive without air.八、“情态动词have done ”用法一览表情态动词完成式用法 例句must have done表示对过去发生的动作进行肯定的推测，意为“一定/准是做了某事”。It must have rained last night, for the ground was wet.I didn

15、t hear the phone. I must have been asleep.could/can not have done表示对过去发生的行为的怀疑和不肯定，意为:不可能发生了某事。He cant have turned up at the party, for he went abroad.could have done 表示：“本来可以做某事，却没有做。”You could have helped him.may/might have donemay/might not have done 表示：“过去可能做过某事，但不肯定。”或“过去可能没有做过某事”。不用于疑问句。Its to

16、o late. He may have gone to bed.He might not have finished the work. should/ought to have doneshouldnt/oughtnt to have done 用于肯定句时，表示“本该做某事，而实际上没做”；用于否定句时，则表示“不该做的事却做了”。You should have come to the meeting earlier.You shouldnt have told her the truth. She is sad now.The plant is dead. You should have

17、 given it more water.neednt have done表示“做了本没有必要做的事，却做了”。You neednt have taken a taxi here, for it was very near to my house.had better have done 用于事后的建议，含轻微责备的口吻，意为“当时最好做了某事就好了”。You had better have started earlier.would rather have done表示“当时最好做了某事就好了”。I would rather have taken his advice.would like/

18、love to have done表示过去愿意做某事，但未做。I would love to have gone to the party last night but I had to work extra hours to finish a report. 九、情态动词其他用法要点1.could/can not but do sth .表示“不得不，只好”.I could not but choose to go. 2.may well do sth.表示“很可能”，相当于be likely to do sth.3.may as well do sth.意为“最好，倒不如”.You may

19、 as well do it at once. I have nothing to do, so I may as well go to bed.4.can not (never)+enough/too表示“再也不为过，越越好”.5.need/dare 的用法need和dare两者即可用作情态动词也可用作行为动词，通常用于否定句和疑问句中.He neednt walk so fast. He doesnt need to walk so fast. I darent ask her for a rise.我不敢请求她加薪.How did you dare to tell her that? I

20、 wonder whether he need send it immediately.You neednt finish that work today.I dare say 是习惯用法，意为“我想，大概”.need作为行为动词时，还可表示“需要”，后接动名词主动形式表示被动含义.The garden doesnt need watering at the moment.部分情态动词的否定式是情态动词中的考点之一.mustnt 不准, 禁止 neednt 没必要 ( = dont have to )cant 不能; 不可能 may not 不可以; 可能不 shouldnt 不应该 ( =

21、ought not to )常考点清单三 虚拟语气一、虚拟语气在非真实条件句中虚拟条件句（if）主句例句与现在事实相反的假设did/wereshould/would/could/might+动词原形If I were you, I would go with her.与过去事实相反的假设had doneshould/could等+have doneIf you had taken my advice, you would not have failed in this exam.与将来事实相反的假设did/were to do/should doshould/would/could/might

22、 doIf it were to rain tomorrow, the sports meeting would be put off.使用虚拟条件句时要注意以下几点：1.错综时间虚拟语气：主从时间不一致，要对应各自的形式If you had studied hard before, you would be a college student now.If it hadnt rained last night, it would be very warm today.2.如果条件句中有were, had, should 这三个单词时，可把if 省略，把这三个单词放在句首，变为倒装句式.Wer

23、e I you, I would take his advice. Had I been there then, I would have helped her.Should he come tomorrow, I would have a word with him.3.介词with, without, but for用于虚拟语气中，介词短语代替条件状语从句.Without sunlight, there would be no living things on the earth.But for your help, we could not have finished the work ahead of time.But for their help, we D the program in time. (2009, 安徽卷) A. can not B. will not C. had not finished D. could not have finished 4.含蓄条件虚拟语气I was ill that day. Otherwise, I would have taken part in the sports meet.I migh