情態(tài)動(dòng)詞的基本用法

1、情態(tài)動(dòng)詞的基本用法情態(tài)動(dòng)詞的特點(diǎn)沒(méi)有人稱和數(shù)的變化。有些情態(tài)動(dòng)詞有過(guò)去式的變化：will would , can could , may might , dare daredcan (could)表示能力。Two eyes can see more than one.表示允許。Can I have a look at your new pen?Can (Could) you lend me a hand?表驚異、懷疑、不相信等態(tài)度。主要用于否定句、疑問(wèn)句或感嘆句中。Where can (could) they have gone to?He can t (couldn t) be over s

2、ixty.How can you be so careless?表示猜測(cè) (肯定句把握較??；否定句幾乎為100% 把握 ) The temperature can fall to 10 .You can t be serious.may (might)1表允許， might 是 may 的過(guò)去式 ; 用在疑問(wèn)中比may 委婉、客氣。You may take whatever you like.He told me that I might smoke in the room.表可能（事實(shí)上） 。 語(yǔ)氣不肯定。He may be at home. 他可能在家。 She may not know

3、about it.I am afraid they might not agree with him.They might be having a meeting, but I m not sure.must表必須（主觀意志）We must do everything we can to help him.You mustnt talk to her like that.-Must we hand in our exercise books now?-No, you needn t. / No, you don t have to.表示很有把握的推斷，意為“想必、準(zhǔn)是、一定”等，只用于肯定句。

4、have (has)got to 必須 , 不得不。過(guò)去式為had to。He must be ill. He looks so pale.She must have a lot of money, for she drives a BMW.shall表征詢意見(jiàn)，用于第一、第三人稱疑問(wèn)句。Shall I get you some tea?have (has)to：Shall the boy wait outside?Its a fine day. Lets go fishing, shall we?表說(shuō)話人的意愿，有“命令、允諾、警告、決心”等意思，用于第二、第三人稱陳述句。You shall

5、 do as I say. （命令）You shall have the English book as soon as I finish it. （允諾）He shall be sorry for it one day, I tell you.（警告）Everything that he owns shall be taken away from him. （決心）will表意愿，用于各種人稱陳述句。I will do anything for you.If you will read the book, I ll lend it to you.表請(qǐng)求，用于疑問(wèn)句。Dont smoke in

6、 the meeting room, will you?Won t you drink some more coffee?表示某種傾向或習(xí)慣性動(dòng)作。Fish will die out of water. The door won t open.would表意愿。They would not let him in because he was poorly dressed.表委婉地提出請(qǐng)求、建議或看法。Would you like another glass of beer?表過(guò)去反復(fù)發(fā)生的動(dòng)作或過(guò)去的一種傾向。Every time she was in trouble, she would g

7、o to him for help.should表義務(wù)。意為“應(yīng)該” ，用于各種人稱。You should listen to the doctors advice.你應(yīng)該聽(tīng)從醫(yī)生建議的。You should study the article carefully.你應(yīng)該仔細(xì)讀那篇文章。表推測(cè)，意為“想必一定、照說(shuō)應(yīng)該、估計(jì)”等。The film should be very good as it is starring first-class actors.那部電影想必很棒，都是一流的演員。They should be home by now.現(xiàn)在他們應(yīng)該已經(jīng)到家了ought to意為“應(yīng)該

8、” ，口氣比 should 稍重。Ought you to smoke so much?你應(yīng)該抽這樣多煙嗎？You ought to write to the mayor.您應(yīng)該給市長(zhǎng)寫(xiě)信。表推測(cè)，暗含很大的可能。She ought to know his telephone number.她應(yīng)該知道他的電話號(hào)碼。used to過(guò)去常常 , 現(xiàn)在不復(fù)發(fā)生或存在。The Greeks used to worship several gods. 過(guò)去 ,希臘人崇奉好幾種神。He used to smoke. 他過(guò)去抽煙（現(xiàn)在不抽了）。情態(tài)動(dòng)詞的推測(cè)用法 肯定句中：must ( 一定 )， may

9、( 可能 )， might/could ( 也許，或許 ) 其語(yǔ)氣的肯定程度依次遞減。其中， might 和 could 并非過(guò)去時(shí)態(tài)，只是語(yǔ)氣較為委婉或可能性較小對(duì)當(dāng)前行為、情況或狀態(tài)的推測(cè)： must /may /might /could + do/beHe must/may/might/could be in the reading room. 他肯定 /可能 /也許在閱覽室里。 I must look funny in this hat. 我戴這頂帽子看起來(lái)一定很滑稽。 對(duì)此時(shí)此刻正在進(jìn)行的動(dòng)作的推測(cè)：must /may/ might/ could + be doing想必 /可能正在

10、He must /may/ might/ could be watching TV at this time.他此時(shí)一定 /可能 /或許在看電視。They must be waiting for us.他們肯定在等著我們。 對(duì)過(guò)去發(fā)生的事情的推測(cè)：must /may /might /could + have +過(guò)去分詞想必 /可能已經(jīng)They must have arrived by now.現(xiàn)在他們肯定已到了。You look very tired. You must have stayed up last night.看上去你很疲勞，你昨晚一定熬夜了。You may have read a

11、bout it in the papers. 你可能在報(bào)上已讀到這件事了。 過(guò)去的一段時(shí)間內(nèi)一直在進(jìn)行的動(dòng)作：must/may /might/ could + have + been +doing想必 /可能一直在They are sweating all over. They must have been working in the fields.他們渾身是汗，準(zhǔn)是在地里勞動(dòng)來(lái)著。He may have been waiting for us for an hour.他可能等我們一小時(shí)了。2否定句中：can/could not不可能，想必不會(huì)may/might not可能不對(duì)當(dāng)前行為、情況

12、或狀態(tài)的推測(cè)：can/could not+ 動(dòng)詞原形不可能，想必不會(huì)may/might not +動(dòng)詞原形可能不He may not be busy now.也許他現(xiàn)在不忙。He can not be busy now.他現(xiàn)在一定不忙。He can t be in the reading room. I saw him on the playground just now.他不可能在閱覽室里，我剛看到他在操場(chǎng)上。對(duì)此時(shí)此刻正在進(jìn)行的動(dòng)作的推測(cè)：can/could not + be doing不可能，想必不會(huì)在干某事may/might not + be doing可能沒(méi)在干某事They can

13、t be telling the truth.他們不可能在說(shuō)真話。They may not be telling the truth.他們可能沒(méi)在說(shuō)真話。對(duì)過(guò)去發(fā)生的事情的推測(cè)：can/could not + have + 過(guò)去分詞 不可能，想必不會(huì)做過(guò)某事 may/might not + have + 過(guò)去分詞 可能沒(méi)干過(guò)某事He can t have finished the work so soon.這項(xiàng)工作他不可能完成得這樣快。He may not have achieved all his aims. But his effort is a good one.他可能沒(méi)達(dá)到他的全部目的

14、，但他還是認(rèn)真做了努力的。過(guò)去的一段時(shí)間內(nèi)一直在進(jìn)行的動(dòng)作：can t /couldn t/may not have been doingHe can t have been waiting for us so long.他不可能等我們那么長(zhǎng)時(shí)間。3疑問(wèn)句中：常用 can/could 來(lái)表示說(shuō)話人的猜疑、懷疑或不肯定的語(yǔ)氣 對(duì)當(dāng)前行為、情況或狀態(tài)的推測(cè)：can/could +主語(yǔ) + do/beWhere can he be now?Can it be true?他現(xiàn)在會(huì)在哪里呢？那會(huì)是真的嗎？ 對(duì)此時(shí)此刻正在進(jìn)行的動(dòng)作的推測(cè)：can/could + 主語(yǔ) + be doingIt s so

15、late. Can Tom be reading?這么晚了，湯姆還在看書(shū)嗎？What can he be doing?他可能在做什么呢？ 對(duì)過(guò)去發(fā)生的事情的推測(cè)：can/could + 主語(yǔ) +have doneCan she have told a lie?Where can she have gone?她會(huì)不會(huì)說(shuō)謊了？她會(huì)上哪兒去了呢？情態(tài)動(dòng)詞的辨析need 和 dare用作情態(tài)動(dòng)詞Need he go yesterday? 昨天他有去的必要嗎?I don t think you need worry.She dare not go out alone at night.How dare

16、you say I m unfair?用作實(shí)義動(dòng)詞She needs the work done before tomorrow.她必須在明天以前找人完成這項(xiàng)工作。The table needs painting (to be painted.).I dare say he ll come again.can 和 be able tobe able to 表示經(jīng)過(guò)努力后, 能夠做到 ; be able to 有多種形式的變化。can1.表示體力或腦力方面的能力;表示允許、可能性。could 是 can 的過(guò)去式 , 表示過(guò)去有能力及過(guò)去存在的可能性；用于疑問(wèn)句表示委婉地提出問(wèn)題。The fir

17、e spread through the hotel very quickly but everyone was able to get out. Will you stay for lunch? Sorry, I cant. My brother is coming to see me.must 和 have tomust 表示主觀意志，而have to 表示由于客觀因素。I told her that she must give up smoking.We had to get everything ready that night.would 和 used to1） used to “過(guò)

18、去常?！?, 與現(xiàn)在事實(shí)相反; would 表過(guò)去意愿。People used to think that the earth was flat.She would go out for a walk in the morning when she was in the country.易錯(cuò)點(diǎn)點(diǎn)撥：1情態(tài)動(dòng)詞無(wú)論是表達(dá)“推測(cè)和可能性” ，還是表達(dá)“虛擬”這一概念，只要是對(duì)過(guò)去已經(jīng)發(fā)生的事情進(jìn)行描述，一律用“情態(tài)動(dòng)詞 +have done”這一結(jié)構(gòu)；對(duì)現(xiàn)在或?qū)?lái)的事情進(jìn)行描述，用“情態(tài)動(dòng)詞 +動(dòng)詞或系動(dòng)詞原形” 。2should (not) / ought (not) to 在中表示根據(jù)常規(guī)或常識(shí)推測(cè)，表示“某事應(yīng)該或不應(yīng)該發(fā)生”，語(yǔ)氣比 must 或 can t / couldn t 稍弱。3. can, could 表達(dá)推測(cè)時(shí)， 一般用于疑問(wèn)句和否定句中；can 用于肯定句中表示一種理論上的可能性，并不牽涉是否真的會(huì)發(fā)生， 在這種用法中 can 只