情態(tài)動(dòng)詞和虛擬語氣

1、情態(tài)動(dòng)詞和虛擬語氣備課者：丁杰?？键c(diǎn)清單 情態(tài)動(dòng)詞的類型和特征情態(tài)動(dòng)詞的類型一、 情態(tài)動(dòng)詞有：must, cancould,may(might),ought to, had better, shall(should),will(would),have(has) to, used to, need, dare二、 情態(tài)動(dòng)詞的特點(diǎn)1.有一定的詞義,但不能單獨(dú)作謂語,他們要和行為動(dòng)詞或連系動(dòng)詞連用,構(gòu)成謂語，后面接動(dòng)詞原形.2.沒有人稱和數(shù)的變化（除了have to以外）.3.情態(tài)動(dòng)詞一般有時(shí)態(tài)變化（除must, ought to以外）.常考點(diǎn)清單二 情態(tài)動(dòng)詞用法要點(diǎn)一、 表能力（can, be a

2、ble to）1.can有兩種時(shí)態(tài)：can/could2.be able to有更多的時(shí)態(tài)：was (were) able to/will be able to/have been able to.3.表示過去有能力并且成功地做了某事，要用was/were able to相當(dāng)于succeeded in doing something./ manage to do sth. 而不能用could.二、 表推測（可能性）：can/could, may/might , must, should(ought to)1.can(could)常有于否定句和疑問句，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，準(zhǔn)是”，在否定句中，cant 表示“不可能”，may not表示“可能不”. 比較：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，但表示客觀理論上的可能性;may用于肯定句中，表示具體理論上的可能性.結(jié)構(gòu)：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 表推測用于肯定句，否定句用cant/couldnt5.must have done/must do something/mu

5、st be doing something的反意疑問句與must 后面的動(dòng)詞保持一致. 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,陜西卷) A. is he B. isnt he C.

6、 must he D. mustnt he Hi, Tom. Any idea where Jane is? (2009,重慶卷) 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?你非得弄出這么大的聲響嗎？三、表示必要性 must/have to1.must 表“必須”,是主觀上的認(rèn)識. 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. (委婉的拒絕可用：Sorry, but I am using it Now.或Youd better not.)2.have to 表“不得不”，是客觀上的認(rèn)識.dont

8、have to =dont need to do something =neednt do something四、 表示請求、允許、允諾1.shall 用于第一稱或第三稱的疑問句，用于征求對方意見. 結(jié)構(gòu)是：shall I/we/he/ she / they Shall we go to the movie tonight? Shall the driver wait outside? 司機(jī)在外面等著可以嗎？2.shall 用于陳述句中的二、三人稱，表許諾，命令，警告，威脅等. You shall have this book tomorrow. You shall not have the

9、computer if you dont take good care of it.3.當(dāng)宣布法律、法規(guī)的規(guī)定時(shí)，也要用shall.4.Could /Might I borrow your dictionary ? Yes, of course you can/may. No, Im afraid not.不可說：Yes, you could/might. 回答允許時(shí)，用could/might 表委婉是不恰當(dāng)?shù)?五、had better, should/ought to的用法這三者都可以用來提建議，語氣強(qiáng)弱順序：had better<should<ought toshould/ou

10、ght to的用法：1.常用來表示因?yàn)橛胸?zé)任、義務(wù)，而應(yīng)該做某事. 如：You shouldnt leave a baby alone in the house. The students ought to obey the school rules.2.表示勸告或建議，“應(yīng)當(dāng)，宜于”.如：He should stop smoking.3.表猜測，“理應(yīng)，按理說應(yīng)該，總應(yīng)該”.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還有“竟然，竟會(huì)”的意思，表“驚訝，憤怒”等情緒. Why/How+ should?表示“竟會(huì)，怎么會(huì)”. 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.過去將要 2.過去常常 3.表決心，決意，過去的意愿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.交際用語中表達(dá)請求，許可，語氣客氣，委婉. Wou

13、ld you do me a favor? 請幫我一下，好嗎？七、will 的用法1.表意愿 Write to me when you get home. I will. I will help you. 2.現(xiàn)在或?qū)淼牧?xí)慣 The old man will sit by the window for hours. 3.臨時(shí)作出的決定 I heard our teacher was ill. Well, I will see him this afternoon. Ann is in hospital. (2009，江蘇卷) 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.表示必然的趨勢 Fish will die without water. Human beings will not survive without air.八、“情態(tài)動(dòng)詞have done ”用法一覽表情態(tài)動(dòng)詞完成式用法 例句must have done表示對過去發(fā)生的動(dòng)作進(jìn)行肯定的推測，意為“一定/準(zhǔn)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表示對過去發(fā)生的行為的懷疑和不肯定，意為:不可能發(fā)生了某事。He cant have turned up at the party, for he went abroad.could have done 表示：“本來可以做某事，卻沒有做?！盰ou could have helped him.may/might have donemay/might not have done 表示：“過去可能做過某事，但不肯定?！被颉斑^去可能沒有做過某事”。不用于疑問句。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 用于肯定句時(shí)，表示“本該做某事，而實(shí)際上沒做”；用于否定句時(shí)，則表示“不該做的事卻做了”。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“做了本沒有必要做的事，卻做了”。You neednt have taken a taxi here, for it was very near to my house.had better have done 用于事后的建議，含輕微責(zé)備的口吻，意為“當(dāng)時(shí)最好做了某事就好了”。You had better have started earlier.would rather have done表示“當(dāng)時(shí)最好做了某事就好了”。I would rather have taken his advice.would like/

18、love to have done表示過去愿意做某事，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、情態(tài)動(dòng)詞其他用法要點(diǎn)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”，相當(dāng)于be likely to do sth.3.may as well do sth.意為“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“再也不為過，越越好”.5.need/dare 的用法need和dare兩者即可用作情態(tài)動(dòng)詞也可用作行為動(dòng)詞，通常用于否定句和疑問句中.He neednt walk so fast. He doesnt need to walk so fast. I darent ask her for a rise.我不敢請求她加薪.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 是習(xí)慣用法，意為“我想，大概”.need作為行為動(dòng)詞時(shí)，還可表示“需要”，后接動(dòng)名詞主動(dòng)形式表示被動(dòng)含義.The garden doesnt need watering at the moment.部分情態(tài)動(dòng)詞的否定式是情態(tài)動(dòng)詞中的考點(diǎn)之一.mustnt 不準(zhǔn), 禁止 neednt 沒必要 ( = dont have to )cant 不能; 不可能 may not 不可以; 可能不 shouldnt 不應(yīng)該 ( =

21、ought not to )?？键c(diǎn)清單三 虛擬語氣一、虛擬語氣在非真實(shí)條件句中虛擬條件句（if）主句例句與現(xiàn)在事實(shí)相反的假設(shè)did/wereshould/would/could/might+動(dòng)詞原形If I were you, I would go with her.與過去事實(shí)相反的假設(shè)had doneshould/could等+have doneIf you had taken my advice, you would not have failed in this exam.與將來事實(shí)相反的假設(shè)did/were to do/should doshould/would/could/might

22、 doIf it were to rain tomorrow, the sports meeting would be put off.使用虛擬條件句時(shí)要注意以下幾點(diǎn)：1.錯(cuò)綜時(shí)間虛擬語氣：主從時(shí)間不一致，要對應(yīng)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.如果條件句中有were, had, should 這三個(gè)單詞時(shí)，可把if 省略，把這三個(gè)單詞放在句首，變?yōu)榈寡b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.介詞with, without, but for用于虛擬語氣中，介詞短語代替條件狀語從句.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.含蓄條件虛擬語氣I was ill that day. Otherwise, I would have taken part in the sports meet.I migh