情態(tài)動詞的用法

1、情態(tài)動詞的用法12009-05-27 09:051.情態(tài)動詞的用法 :can, could, may, might, must, ought to, shall, should, will, would, need, dare etc.2 情態(tài)動詞的語法特征：1） 情態(tài)動詞不能表示正在發(fā)生或已經(jīng)發(fā)生的事情，只表示期待或估計某事的發(fā)生。2） 情態(tài)動詞 除ought 和have 外，后面只能接不帶to 的不定式。3） 情態(tài)動詞沒有人稱，數(shù)的變化，即情態(tài)動詞第三人稱單數(shù)不加-s。4） 情態(tài)動詞沒有非謂語形式，即沒有不定式，分詞等形式3.can &could1)表能力（ability)eg.

2、a. I can speak English1).can, could 表示能力,可能, 只用于現(xiàn)在式和過去(could). be able to可以用于各種時態(tài)。表過去的能力，用was/were able to表將來的能力，用shall/will be able to e.g.a. They will be able to tell you the news soon. 他很快就能告訴你消息了2). 表示成功地做了某事時，只能用was/were able to， 不能用coulde.g. a. He was able to flee Europe before the war broke o

3、ut. = He managed to flee Europe before the war broke out. e.g. a. The moon cant always be at the full. (3).表請求（request)e.g. a. Can you tell me the way to the post office? e.g. a. Could I come to see you tomorrow?-Yes, you can.-No, you cant.4).表允許（permission)e.g. a. Can I come in?e. g. a. He can not

4、but agree. 5) can not but do =>have to 不能不做e. g. a. He can not but agree.6). can not help doing can not help (to) do7).can not (never, hardly) do too 越就越好；無論做都不過分e.g. a. You can not be too careful in the exam. b. You can not praise him too highly. 8).could 加完成式用于肯定句時一般表過去可能完成而卻未完成的動作。e.g. a. I co

5、uld have passed my examination easily but I made too many stupid mistakes.4. may & might1） 表示允許或請求 當表示請求，允許時，might 比may語氣更委婉，否定答語要用must not,表示“不許可”、“不應該”、“不行”。e.g. a.- May I come in?-Yes, you may. -No, you mustnt.2).表示沒有把握的推測. “也許”(用于肯定句或否定句中)注意： might 表示推測時，不表示時態(tài),只是可能性比may 小。 e.g. a. He may be

6、playing football.b. He might be at home.3).may 放在句首，表示祝愿e.g. a. May God bless you! b. May you succeed! = Wish you success!4). may/might as well，后面接不帶to 的不定式，意為"不妨"。 e.g. a. If that is the case, we may as well try. 5)may (might) + have +done 表示對過去發(fā)生行為的推測，含有“想必”、“也許是”的意思。e.g. a. It may have

7、been true.這事也許是真的。 b. He might not have settled the question. 他可能尚未解決那個問題。4.will & would1）will表示經(jīng)常性、習慣性、傾向性，would表示過去的習慣行為。e.g. a. He will sit there hour after hour looking at the traffic go by. b.He would come to see me when he was in Beijing. 2）表示意志，決心或愿望。e.g. a. Surely we will support all the

8、 people in the world in their struggle for peace. b. He would not let me try it . 3）表示對對方的請求，用于第二人稱作主語的疑問句中，would的語氣比will委碗,疑問句中一般用some, 而不是any。e.g. a. would/will you kindly tell me the way to the station?b. Would you like some cake?would like = want to 想要 Would like to do e. g. a Would you like to

9、go with me? 5.shall&should shall的用法1)用于第一,第三人稱征求對方的意愿e.g. a. What shall I wear on the journey? b. When shall he be able to leave the hospital? 2)用于第二、三人稱時表允諾（現(xiàn)已少見)e.g. a. She shall get her share. 她可以得到她的一份。 b. You shall have it back tomorrow.你明天可以將它拿回。 should 的用法1)用于第一人稱疑問句中詢問對方的意愿，但語氣較委婉溫和e.g.

10、a. What should we do now? 我們現(xiàn)在該怎么辦？2)表示應該、必須，常與must 換用。e.g. a. We should (must) master a foreign language at least. 3).should 表示勸告，建議，命令，此時也可用ought to. 在疑問句中，通常用should代替 ought to4) should have done 表示過去應該做 而實際沒有做should not have done 表示過去不該做而實際做了 6.must表推測1) must用在肯定句中表示較有把握的推測，意為"一定"。2) mu

11、st表對現(xiàn)在的狀態(tài)或現(xiàn)在正發(fā)生的事情的推測時， must 后面通常接系動詞be 的原形或行為動詞的進行式。 e.g. a. You have worked hard all day. You must be tired.（對現(xiàn)在情況的推測判斷） b. He must be working in his office. 他一定在辦公室工作呢。 比較： e.g. a. He must be staying thereb. He must stay there.他必須呆在那。3) must 表示對已發(fā)生的事情的推測時，must 要接完成式。 e.g. a. I didn't hear the

12、 phone. I must have been asleep. 4) must表示對過去某時正發(fā)生的事情的推測，must 后面要接不定式的完成進行式。 e.g. a. -Why didn't you answer my phone call? -Well, I must have been sleeping, so I didn't hear it.5) 否定推測用can't。e.g. a. If Tom didn't leave here until five o'clock, he can't be home yet.have tomust

13、1)兩詞都是'必須'的意思，have to 表示客觀的需要， must 表示說話人主觀上的看法，既主觀上的必要。e.g. a. My brother was very ill, so I had to call the doctor in the middle of the night. (客觀上需要做這件事) b. He said that they must work hard. （主觀上要做） 2)have to有人稱、數(shù)、時態(tài)的變化，而must只有一種形式。但must 可用于間接引語中表示過去的必要或義務e.g. a. He had to look after his

14、sister yesterday.3） 在否定結(jié)構(gòu)中： dont have to 表示“不必” mustnt表示 “禁止” e.g. a. You dont have to tell him about it. b. You mustnt tell him about it.8. need&dare這兩詞既可做實義動詞用，又可做情態(tài)動詞用。作為情態(tài)動詞，兩者都只能用于疑問句，否定句和條件句。 need 作實義動詞時后面的不定式必須帶to，而dare作實義動詞用時, 后面的to 時?？梢员皇÷?。 1) 實義動詞:need+ n. / to do sth2) 情態(tài)動詞： need，只用原形

15、need后加do，否定形式為need not。e.g. a. -Need you go yet? -Yes, I must. -No, I needn't.3) need 的被動含義：need, want, require, worth（形容詞）后面接doing也可以表示被動：need doing = need to be done9.情態(tài)動詞的回答方式問句肯定回答否定回答Need you?Yes, I must.No,I needntMust you?Yes, I must. No, I neednt./dont have to. May I ? Yes, of course. No

16、, you mustnt.Could you? Yes, you can. No, you cant.10.情態(tài)動詞表猜測must 用于肯定句can 用于否定句或疑問句6 表示推測的用法can, could, may, might, must 皆可表示推測，其用法如下： 1）情態(tài)動詞+動詞原形。表示對現(xiàn)在或?qū)淼那闆r的推測，此時動詞通常為系動詞。I don't know where she is, she may be in Wuhan. 2）情態(tài)動詞+動詞現(xiàn)在進行時。表示對現(xiàn)在或?qū)碚谶M行的情況進行推測。At this moment, our teacher must be cor

17、recting our exam papers. 這時，我們老師想必在批改試卷。3）情態(tài)動詞+動詞完成時。表示對過去情況的推測。We would have finished this work by the end of next December.明年十二月底前我們很可能已完成這項工作了。The road is wet. It must have rained last night.地是濕的，昨天晚上一定下雨了4）情態(tài)動詞+動詞的現(xiàn)在完成進行時。表示對過去正在發(fā)生事情的推測。Your mother must have been looking for you.你媽媽一定一直在找你。 5）推測

18、的否定形式，疑問形式用can't, couldn't表示。Mike can't have found his car, for he came to work by bus this morning.邁克一定還沒有找回他的車，因為早上他是坐公共汽車來上班的。 注意：could, might表示推測時不表示時態(tài)，其推測的程度不如can, may。 7 情態(tài)動詞+ have +過去分詞1) may(might) have + done sth, can (could) have + done sth表示過去，推測過去時間里可能發(fā)生的事情。Philip may (might)

19、 have been hurt seriously in the car accident.Philip can (could) have been hurt seriously in the car accident.2)must have +done sth，對過去時間里可能發(fā)生的事情的推測，語氣較強，具有"肯定"，"諒必"的意思。-Linda has gone to work, but her bicycle is still here. -She must have gone by bus.4) needn't have done sth

20、 本沒必要做某事I dressed very warmly for the trip, but Ineedn't have done so. The weather was hot.5) would like to have done sth 本打算做某事I would like to have read the article, but I was very busy then. 8 should 和ought to should 和ought to 都為“應該”的意思，可用于各種人稱。 -Ought he to go?-Yes. I think he ought to.表示要求，命

21、令時，語氣由 should（應該）、had better最好）、must（必須）漸強。 9 had better表示"最好"had better 相當于一個助動詞，它只有一種形式，它后面要跟動詞原形。had better do sth .had better not do It is pretty cold. You'd better put on my coat. She'd better not play with the dog. had better have done sth表示與事實相反的結(jié)果，意為"本來最好"。 You had better have come earlier.10 .would rather表示"寧愿"would rather do would rather not dowould rather than 寧愿而不愿。還有would sooner, had rather, had sooner都表示"寧愿"、"寧可"的意思。If I have a choice, I had sooner not continue my studies at