情态动词用法(2)

1、情态动词 1.情态动词不能单独作谓语 2. 后接动词原型 3. 没有人称和数的变化 He runs fast. He can run as fast as a horse. She is waiting for us now. She may be waiting for you now. Tom didnt lose his way in the forest. Tom couldnt have lost his way in the forest.一.表示推测 、可能性 may / might , can / could, must, should, ought to 表示推论和推测程度不

2、同不同的“肯定程度的“ 可能性可按以下层次排列： He is at home. (事实) He must be at home.非常肯定的推断 He could be at home.很可能 He ought to be at home.很可能 He may be at home.仅仅可能而已 He might be at home.或许, 非常不确定 He might not be at home.也许不在家He may not be at home. 比might可能 He couldnt be at home.很可能不在家 He cant be at home.一定不在家He isnt

3、at home.事实 客观客观主观1 “must 来表示近乎肯定的推论。must 后的各种时态(除将来时)可表达所推测的事情发生的时间eg Its half past three. He must be at home. Lets hurry. Mr. Smith must be waiting for you.2.may might 表示对讲的事无多大把握，有些可能。might 的可能性最小eg: They may be staying at Beijing Hotel. He didnt say anything ,but he might have see the surprise in

4、 my face.3 can could 表示推测，用与否认句和疑问句中，eg: The story cant be true. Can / Could he still be working ? can/could假设用于肯定句中，肯定句中表示“可能性不指具体动作，译为“可能会，有时会(见后) 4 shouldought to 表示可能性较大的推测,将来时eg: The book should be out in a month or so. John ought to have left by tomorrow.Shouldought to 还表示“义务，所以不太用与表推测。表示推测情态动

5、词的重要用法.肯定的推测可能的推测否认的推测疑问的推测must 对将来 对现在 对过去情态动词may, might cant, couldntcan, could + V. + V. + have doneshould be + be doing + V. + V. + have done + be doing 可以用not表示“可能不 +V. + V. + have done + be doing+ V. + V. + have done + be doing一.表示推测 ( may / might , can / could, must, should, ought to )1. may

6、(过去式 might) “可能 There may be little water left in the bottle. He thought it might be wise to try his luck there.注意: 1. 可以用might代替may,以表示语气更加不肯定;2. “那个瓶里可能有水吗? May there be any water in the bottle? Can there be any water in the bottle? May I use your cell phone ? (征求许可 ) might2. can (过去式could) “可能会Th

7、at cant be true.What on earth can this mean?注意: 1) 可以用could代替can, 以表示语气婉转;2) This story can be true, but I hardly think it is. This story could be true, but I hardly think it is.3) Our house is on the top of the hill, and in winter the winds can be pretty cold. “有时候会couldntcouldmay / might 4) This m

8、ay not / might not be true. “可能不 This can not be true. “不可能3. must “肯定、 “准是You must be joking, arent you?注意: 1) “他肯定不是在开玩笑. He must not be joking. He cant be joking. No one must be allowed to drive without a driving permit. “不准 2) “他肯定在家吗? Must he be at home? Is it certain that he is at home? Must I

9、 finish it by the end of this week?(必须 Why must you ask me so many questions when Im busy cooking? 偏要 注意: must在疑问句中只能表示 “必须 或表示反感 “(干吗)偏要 “硬要 ; 3) “你肯定会成功. You must succeed. Youre sure to succeed. / It is certain that you will succeed. / Im sure that youll succeed.你必须成功.他必须呆在家里吗?4. should , ought to

10、 “照说应当, “想比一定, “按理应该My new poems should / ought to be out in a month at most. 总 结 表示推测，疑问句中要用cancould); maymight在问句中只能表示请求许可。 表示一次性动作或一时性状态can不用于肯定陈述句中could可以。但can用于肯定陈述句可以表示“有时候可能会.3. 可以用might代替may,以表示语气更加不肯定;4. cant couldnt比may notmight not语气强。5. 表示推测，must不用于否认句换用cant/couldnt，疑问句换句型，也不用于对将来推测换句型。7

11、. 表示推测，should /ought to 比may /might 有更有把握些， 但次于must。 It is six oclock. He may have got up now.It is six twenty . He ought to have got up now.It is a quarter to seven. He must have got up now.He often gets up at about 6 oclock, has breakfast at 6:20 and goes to work at 6:55.50%80%90% 1. I dont know w

12、here she is, she _ be in Wuhan. 2. At this moment, our teacher _ our exam papers. 这时，我们老师想必在批改试卷。 3. The road is wet. It _ last night. (rain) 4. Your mother _ for you.你妈妈一定一直在找你。 maymust be markingmust have rainedmust have been looking5. Philip _ seriously in the car accident. 菲利普可能在车祸中受了重伤.6. -Lind

13、a has gone to work, but her bicycle is still here.-She _ (go) by bus.7. Mike _ his car, for he came to work by bus this morning.迈克一定还没有找回他的车，因为早上他是坐 公共汽车来上班的。may (might) have been hurtmay (might) have gonecant have found高考考题:1. I thought you _like something to read, so I have brought you some books.

14、 A. may B. might C. would D. must 2. Where is my pen? I _it. A. might lose B. would have lost C. should have lost D. must have lost3. I didnt hear the phone. I _asleep A. must be B. must have been C. should be D. should have beenB D B 4. -There were already five people in the car, but they managed t

15、o take me as well. -It _a comfortable journey A. cant be B. shouldnt be C. mustnt have been D. couldnt have been 5. Its nearly seven oclock . Jack _be here at any moment. A. must B. need C. should D. could D C 二.表示必要性,、职责、劝告、建议等 (need, must, should, ought to )1. need “必需 “需要 ; must “必须 You neednt be

16、 here before 9 oclock.注意: 1) “你需要在九点钟以前到达这里. You need be here before 9 oclock. You need to be here before 9 oclock. You must be here before 9 oclock. 2)- Must I hand in the composition at the end of the class? -Yes, you need. -No, you mustnt. Yes, you must.No, you neednt. / Need 2)- Must I hand in t

17、he composition at the end of the class? -Yes, you need. -No, you mustnt. 3) I must study hard at school. (积极) I have to study hard at school. (消极) 总 结表示必需或需要，need不用于肯定陈述句中换用need to。Yes, you must.No, you neednt. / Need2. Must表示必须，不用于否认句中换用neednt，dont need to 或dont have to， 因为must用于否认句表示禁止。3. must vs.

18、 have to 表示必须，must表示主观积极，have to 表示客观消极。时态must只有过去式表示过去和原形表示现在和将来两种，但have to 有多种形式。2. 表示建议、劝告. shall, should , ought to , must Shall we have a break?haveto的用法 1must表示一种主观的需要，而haveto表示一种客观的需要，意思是“不得不。如： I have to attend an important meeting this afternoon. 今天下午我不得不参加一个重要的会议。 Mother is out, so I have

19、to look after the shop. 妈妈不在家，因此我不得不照看商店。 2haveto的否认形式是dont have to, 相当于neednt。如： They dont have to buy a computer at present. 他们目前没有必要买电脑。Lets not bother him, shall we ?You ought to / should follow your teachers advice.You must take plenty of water with you if you want to walk alone into the desert

20、. 三. 请求对方做某事 疑问句中用情态动词can / could , will / would表示请求比用祈使句表示请求婉转、客气.Can / Could you wait a few more days ?Will / Would you please wait a few more days ?四. 表示允许或征询对方许可may / might, can / could (“不准许may not / cant / mustnt)You may / can stay here for the night.-May / Might / Can / Could I have a talk wi

21、th you ?-Yes, you might / could. -No, you might not / couldnt. No, you may not / cant / mustnt.五. 表示能力 can (过去式could ), 比较 be able toYes, you may / can. 1. 泛指能力(具有知识、技巧、本领而能读书、游泳、说英语、踢足球等) I could / was able to swim well when I was only ten.2. We had a holiday yesterday, but couldnt / werent able to

22、 go to the seaside. He didnt agree with me at first, but I was able to persuade him. (=managed to persuade )How many children was he able to save from the flood? (=How many children did he succeed in saving from the flood?)总结：指过去某一次能力，肯定陈述句不 用could，而用was/were able to。六. dare (过去式 dared) “敢于He dare n

23、ot go into the building even in the daytime.How dare you ask me such a question?If you dare say that again, you shall be punished.注意: “他黑夜敢进入那幢大楼. He dare go into the building in the dark night. He dares to go into the building in the dark night. He doesnt dare (to ) tell us the truth. 总 结 1。作情态动词，d

24、are不用于肯定陈述句换用 dare to。但在if条件状语从句肯 定式中常用dare作情态动词。2。作实义动词，dare后面跟带to不式， 但在否认句中to可以省略。七. 表示习惯性动作或状态 will 指现在 “往往 、“总是 、“就会 would 指过去 “常常 “总是 (没暗示现在) used to 指过去 “常常 “总是 (暗示现在不再如此)Hell talk for hours if you give the chance.She would / used to talk with her neighbors as she had breakfast. 八. 情态动词shall的其

25、他用法 shall用于二、三人称,表示说话者的命令、警告、威胁、强制、允诺等; Your money shall be taken away according to the law. Tell him that he shall have the bike tomorrow. 2. Shall用于一、三人称问句中, 表示征求对方意见或指示. Where shall we meet tomorrow morning? Shall he go now or stay behind? Shall I show you around ?九. will (would)用于各种人称,表示意愿,意志. I will stick to my plan though all of you are against it. I told him to give up smoking, but he wouldnt listen.十. 情态动词 + 完成式动词 (指过去的动作或情况) may / might have done sth. 可能做过(了) cant / couldnt have done sth. 不可能做了 must have done sth. 准是做了