【語法透視】：情態(tài)動詞的用法解析

1、語法透視】 :情態(tài)動詞的用法解析must (無詞形變化)(1) 。 表必須， 應(yīng)該,務(wù)必must not(mustnt)表禁止,不許,不準(zhǔn), 不可以。Everyonemust attend the lecture. The work must be finished as soon as possible.You mustnt lend it to others. 注；對 must 問句的回答。-Must I go there now? -Yes, you must.-No ,you n eed nt. n eed not dont have(got) to dont n eed to.2.m

2、ust 表推測一定，必定，一般只用于肯定句，亦即用于疑問句和否定不表 揣測。( 1)對現(xiàn)在 He must be at home now. You must be hungry after the long walk. The Chineselanguage must have the largest number of speakers.(2) 對進行時。 He must be sleeping now(at that time).( 3)對過去時或完成時。It must have rained last night. He must have fallen asleep(then).He

3、must have gone to Beijing yesterday. She must have been young when she got married .注意其反意問句。3 .must 表不可避免的傾向。 All men must die.4 . must 表偏偏，不巧My car must break down 我的車偏偏壞了。have to不得不1. 與 must 的區(qū)別(1)must 表說話人的主觀看法，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.(主觀認為)2.

4、 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I thought I must go there.3.have to 的疑問，否定均須借助于 do。 Does he have to go there now 不說 Has he to gothere now?He has to go there now, doesn t he? The work has to be finished before 10 oclock.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)的動作（即；

5、動作確實做了）。I had to stay at home last night.Can1.表能力I can lift the ston e. I can speak En glish while he cant. Who can play the violin? Hegot up early yesterday so that he could catch the early bus.could 表過去的能力。注；1。can 與 be able to 表能力時的區(qū)別：1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,

6、was able to , has bee n able , will be able to , would be able t 等。be able to 只表能力而 can 還可表可能性， 驚異,許可等。2could 與 was able to 表過去能力的差別：均表過去的能力，但 was（ were）able to 還可表業(yè)已成功的行為（即：動作確實做了） 。2表 許可 You can go now. You can use my dictionary. You can have a rest.-Can I smoke here?-No, you cant.注：用 could 代替 can

7、 在疑問句中，語氣客氣委婉，但在時間上還指現(xiàn)在 .Could youlend me your bike? Could you tell me how to get to the station?注意：回答由 could 引起的問句，仍用 can 而不用 could。-Could you wait a few more minutes?-Yes, I can.3.表猜測可能 ，一般用于疑問句和否定句。-Can the news be true? -It cant be true. Where can he be?注：（1）cant 表不可能，語氣斷然否定。（2）could 在賓語從句中表過去的可

8、能性，其它情況一般還表示現(xiàn)在的可能性只是 語氣比can 委婉和更加不肯定。 I thought he could come .(3) can 亦可用于肯定句表可能， 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) havdone 或 can(could) havbeen(done 用于疑問句或疑問句表 對過去時或完成時的揣測。What can have happened to him ? He ca

9、n not have read the book. He cant have been toBeijing.4.表驚異驚訝:How can you be so impolite? How can you say that?May 表允許許可允諾 (征詢對方許可)。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 來代替 may not 表 示不可以， 禁止。 -May I watch TV after supper?-Y

10、es, you may.(No, you must nt 或 No, you may no t.或 No, youd better no t.)(2)與 can 的比較：may 比 can 更正式。May I know your name? May I (he, we ).?xMay you .? (May you have a good journey 此處表祝愿)(3)。 might 代替 may 用于疑問句，更客氣禮貌些，回答時仍用may。-Might I use your telephone? -Yes, you may .(4) might not 不表示不允許2表可能。(1)用于肯

11、定句和否定句(因為 May I?表征詢許可)。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 cant catch the fast train.(2) 用 might 語氣更加不肯定， 但指現(xiàn)在或?qū)恚?只有在賓語從句中 might do( be) 才表示過去可能性。 He might come today(tomorrow). She might have some fever .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 cant be true .may(might) (n ot)+have don e(bee n 表對過去或完成時的揣測。 Something may havehappened