【語(yǔ)法透視】：情態(tài)動(dòng)詞的用法解析

1、【語(yǔ)法透視】:情態(tài)動(dòng)詞的用法解析must （無(wú)詞形變化）（1）。表"必須"，"應(yīng)該"，"務(wù)必" must not(mustn't)表"禁止"，"不許"，"不準(zhǔn)"，"不可以"。 Everyone must attend the lecture. The work must be finished as soon as possible.You mustn't lend it to others.注；對(duì)must問(wèn)句的回答。 -Must I go

2、 there now?-Yes, you must.-No ,you needn't. need not don't have(got) to don't need to.2.must表推測(cè)"一定"，"必定"，一般只用于肯定句，亦即用于疑問(wèn)句和否定不表揣測(cè)。（1）對(duì)現(xiàn)在He must be at home now. You must be hungry after the long walk.The Chinese language must have the largest number of speakers. (2)對(duì)進(jìn)行時(shí)

3、。 He must be sleeping now(at that time).（3）對(duì)過(guò)去時(shí)或完成時(shí)。It must have rained last night. He must have fallen asleep(then).He must have gone to Beijing yesterday. She must have been young when she got married .注意其反意問(wèn)句。3 .must表不可避免的傾向。 All men must die.4 . must 表"偏偏"，"不巧" My car must br

4、eak down.我的車(chē)偏偏壞了。have to "不得不"1. 與must的區(qū)別 （1）must表說(shuō)話人的主觀看法，而have to表客觀需要。比較：I have to stop smoking .(外界壓力，客觀情況使然)I must stop smoking.（主觀認(rèn)為）2.must只有一種形式而have to有更多的形式have to, has to ,had to ,will have to 等等。I thought I must go there.3.have to 的疑問(wèn)，否定均須借助于do。 Does he have to go there now ?不說(shuō)H

5、as he to go there now?He has to go there now, doesnt he? The work has to be finished before 10 o'clock.4.must與had to的差別： had to還可以表示業(yè)已完成或?qū)崿F(xiàn)的動(dòng)作（即；動(dòng)作確實(shí)做了）。I had to stay at home last night.Can 1.表"能力"I can lift the stone. I can speak English while he can't. Who can play the violin? He

6、 got up early yesterday so that he could catch the early bus.could 表過(guò)去的能力。注；1。can 與be able to表能力時(shí)的區(qū)別： 形式上；can有兩種形式can 與could，而be able to有更多的形式。is(are)able to, was able to , has been able , will be able to , would be able to 等。be able to 只表能力而can 還可表"可能性"，"驚異","許可"等。 cou

7、ld與was able to表過(guò)去能力的差別：均表過(guò)去的能力，但was（were）able to還可表業(yè)已成功的行為（即：動(dòng)作確實(shí)做了）。2表"許可"You can go now. You can use my dictionary. You can have a rest.-Can I smoke here?-No, you can't.注：用could代替can在疑問(wèn)句中，語(yǔ)氣客氣委婉，但在時(shí)間上還指現(xiàn)在.Could you lend me your bike? Could you tell me how to get to the station?注意：回答由

8、could引起的問(wèn)句，仍用can 而不用could。-Could you wait a few more minutes?-Yes, I can.3.表猜測(cè)"可能"，一般用于疑問(wèn)句和否定句。-Can the news be true? -It can't be true. Where can he be?注：(1)can't表"不可能"，語(yǔ)氣斷然否定。(2) could在賓語(yǔ)從句中表過(guò)去的可能性，其它情況一般還表示現(xiàn)在的可能性只是語(yǔ)氣比can委婉和更加不肯定。 I thought he could come .(3) can 亦可用于肯定

9、句表可能，但表示的是邏輯推理上的可能性（或理論上的），非主觀臆斷。There can be no noise on the moon because of sound being carried by the air .(4) can(could)have done或can(could)have been(done)用于疑問(wèn)句或疑問(wèn)句表對(duì)過(guò)去時(shí)或完成時(shí)的揣測(cè)。What can have happened to him ? He can not have read the book. He can't have been to Beijing.4.表"驚異""

10、;驚訝"：How can you be so impolite? How can you say that?May 表"允許""許可""允諾"（征詢(xún)對(duì)方許可）。You may go now . May I use your bike? You may keep the book for 2 weeks .注意：(1)其否定形式may not表示不可以，但更常用must not來(lái)代替may not表示"不可以"，"禁止"。 -May I watch TV after supper?-Ye

11、s, you may.(No, you mustn't .或No, you may not.或No, you'd better not.)(2)與can的比較：may比can更正式。May I know your name? May I (he, we).?×May you.? (May you have a good journey! 此處表祝愿)（3）。might代替may用于疑問(wèn)句，更客氣禮貌些，回答時(shí)仍用may。-Might I use your telephone? -Yes, you may .(4)might not 不表示"不允許"

12、2表"可能"。（1）用于肯定句和否定句（因?yàn)镸ay I?表征詢(xún)?cè)S可）。The news may be true . He may not be at home now. I think he may come today(tomorrow).However fast you may run, you can't catch the fast train.(2)用might語(yǔ)氣更加不肯定，但指現(xiàn)在或?qū)?lái)，只有在賓語(yǔ)從句中might do（be）才表示過(guò)去可能性。 He might come today(tomorrow). She might have some fe

13、ver .I thought you might like something to read, so I brought some books for you .She said she might not be at home. I might be busy tomorrow.(3)may not 與cannot的區(qū)別： may not"可能不"，cannot "不可能"。比較The news may not be true.The news can't be true .(4) may(might)(not)+have done(been)表對(duì)過(guò)去或完成時(shí)的揣測(cè)。Someth