1、語法專練-情態動詞情態動詞的用法(一)情態動詞分為三種情況：1.只用作情態動詞的有 must, can/could, may/might, ought to, be able to2.既可作情態動詞又可作實義動詞的有need, dare，have/had to, used to；3.既可作情態動詞又可作助動詞的有shall/should/will/would。情態動詞不能單獨作謂語，需要和動詞（行為動詞或系動詞）連用，構成謂語。一、情態動詞的基本用法1.can和could的用法1）表示能力或客觀可能性，還可以表示請求和允許。如：Man cannot live without air.人沒有空氣

2、不能活。2）表示驚異、懷疑、不相信的態度（主要用在否定句、疑問句或驚嘆句中）。如：Can this be true? 這能是真的嗎？2.may和might的用法1）表示許可。在表示請求、允許時，might比may語氣更委婉一些，否定回答時要用mustnt，表示“不可以，禁止、阻止”之意。如：Might I use your pen?我能用你的鋼筆嗎？No,you mustnt.不，你不允許。2）用于祈使句中表示祝愿。如：May you succeed! 祝你成功！3.must和have to的用法1）表示必須、必要。回答must引出的問句時，如果是否定的回答，不能用mustnt，而要用need

3、nt或dont have to。如：Must we hand in our English exercise books?我們必須交英語作業嗎？Yes,you must.（No,you dont have to.）是的，你必須要交。（不，你不必）。2）have to的含義與must相似，兩者往往可以互換使用，但must與have to有下列幾點不同：must表示的是說話人的主觀看法，而have to則往往強調客觀需要。must只有一種形式，have則涉及人稱、時態等方面的變化形式。二者的否定意義不大相同。如：You mustnt go.（帶有很強的語氣，表示“禁止、不允許”）你不許走。You

4、dont have to go.（表示“不必”）你不必走。詢問對方的意見時應用must。如：Must I clean all the room?我必須清潔房間嗎？4.shall和should的用法1）shall用于第一人稱，表示征求對方的意愿。如：What shall we do this evening?今晚我們要做什么？2）shall 用于第二、第三人稱陳述句中，表示說話人給對方的命令、警告、允諾或威脅。如要反映客觀情況或涉及法律、義務和規定時一般用ought to。在疑問句中，通常用should代替ought to。如：You shall fail if you dont work ha

5、rder.（警告）如果你不努力點，你就會失敗。5.will和would的用法1）表示請求、建議等，would比will委婉客氣。如：Would you pass me the book? 能把這本書遞給我嗎?2）表示意志、愿望、決心、料想或猜想。如：I hope I would fly in the sky.我希望我能在天空飛翔。3）用“will be”和“will + have + 過去分詞”的結構表示推測，主要用于第二、三人稱。前者表示對目前情況的推測，后者表示對已經完成的動作或事態的推測。如：He will have arrived by now.目前他應該已經到了。4）would可表示

6、過去反復發生的動作或某種傾向。would表示“過去習慣”時比used to正式，并沒有“現已無此習慣”的含義，帶would的句子不宜用在故事開頭。如：During the vacation he would visit me every week.在假期的時候，他每周都來看我。注意：情態動詞用于疑問句進行回答時，出現了異化現象，此時回答在某個角度不能繼續使用該情態動詞，而改用別的動詞。見下表：疑問句式 肯定回答 否定回答Can/Could you do sth.? Yes,I/we can/could. No,I/we cant/couldnt.May I do sth.? Yes,you m

7、ay. No,you mustnt/may notMust I/we do sth.? Yes,you must. No,you neednt/dont have to.Need I do sth.? Yes,you must. No,you neednt/dont have to.Will/Would you do sth.? Sure./Certainly./Yes,of course. Sorry ,but./Im afraid I cant.Shall we/I/he/they do sth.? Yes ,please./Go ahead. Youd better not .Sorry

8、 ,but.Ought you to.? Yes,you should. No,you shouldnt.二、比較can, could, may, might, must表示判斷的用法從上述講解中我們可以看到很多情態動詞都可以用來表示可能性或一種推斷。1.must用于肯定判斷，后跟動詞原形表示對于現在情況的肯定判斷；而結構“must +be + doing”表示“想必正在做某事”。如：Where is Mr Li now? 李老師在哪兒？He must be working in his class,I think.我想他一定正在班里。2.may/might后跟動詞原形表示對于現在情況的可能性

9、推斷。如：Im not sure whether he will come today. He may/might be ill today.我不確定是否他今天會來，他可能生病了。3.can/could用于否定句或疑問句，后跟動詞原形表示對于現在或當時情況的否定或疑問性推測。如：Tom has gone to Beijing, so you cant see him in our school now.湯姆去了北京，所以你肯定不能在我們學校看見他。4.can表示一般性的、理論上存在的可能，而might則表示正在發生或將要發生的具體可能性。A wise man can sometimes mak

10、e a mistake.聰明人有時也會犯錯誤。I might go to Beijing by air next week.下星期我可能乘飛機去北京。5.cant 表示不可能，而may not表示可能不。He cant be only fifteen.他不可能只有15歲。（可能16、17、18歲）He may not be only fifteen.他可能不止15歲。（可能15歲，也可能16歲）情態動詞表示猜測時語氣從強到弱的順序是: must, will, would, ought to, should, can, may, could, might.情態動詞小練（一）1. _ it be

11、Li Ping who broke the glass?No. It _ be Wu Dong who did it. A. Can; must B. Must; need C. May; must D. Need; can 2. Dont forget to visit me when you come to Beijing._. A. I dont B. I wont C. I cant D. I havent3. Could I use your bike?Yes, surely you _. A. might B. will C. can D. should4. Her brother

12、 _ be at home now, because he was seen playing basketball in the stadium just now. A. mustnt B. neednt C. cant D. shouldnt5. When can you get my car repaired? I need it tomorrow morning. It _ be ready by 8:00. A. can B. need C. might D. should 6. Are you coming for dinner?Im not quite sure. I _ go t

13、o my uncles instead. A. must B. would C. should D. might7. Dont believe him. What he said _ be true. A. mustnt B. neednt C. shouldnt D. may not8. _ I go home now, sir?No, you _. You should finish the composition first. A. Might; wouldnt B. May; had better not C. Must; mustnt D. Need; mustnt9. _ he u

14、se your bike?Certainly. Here is the key. A. Shall B. Must C. Will D. Does10. I thought you _ like something to read, so I have brought you some books. A. may B. might C. could D. mustKey : 1-5 ABCCD 6-10 DDBAB情態動詞（二）ought to的用法ought沒有時態和人稱的變化，后面須跟帶to的不定式。其具體用法如下：1）用于第一人稱，表示有責任或有必要去做某事，與should相比，語氣較弱

15、。如：We ought to be more careful with our homework.我們應當更加認真地做作業。2）用于第二、三人稱，表示建議或勸告。如：You ought to follow Mr Wangs advice.你應當聽王老師的話。3）表示對現在或將來某種可能性的推測，這種推測是可信的。如：Henry ought to be here soon. He left home at six.亨利應當是很快就到，他六點就從家里出來了。4）后接動詞不定式完成式，表示對過去存在的某種可能性的推測，或指過去該做而未做的事情，意思是“早應該，本應該”。若是否定句，則表示發生了不該發

16、生的事。如：Im sorry.I ought to have phoned to tell you I was coming.對不起，我本應該先給你打個電話告訴你我要來。5）ought to后可接不定式進行時，表示“應該在（立即）”，這樣用時語氣比should嚴肅。如：You oughtnt to be talking so much. 你不應當說這么多話。6）用來表達客觀上難以實現或不能實現的愿望，與虛擬語氣相似。如： I love summer! It ought to be summer all the year.我喜歡夏天，全年都應是夏天。情態動詞+have+過去分詞 “情態動詞+ha

17、ve done ”表示推測、后悔、遺憾、責備等語氣。也是語法熱點之一，下面我們就來逐個擊破它。1)may(might)have+donesth /can(could)have+donesth表示過去，推測過去時間里可能發生的事情。Philipmay(might)havebeenhurtseriouslyinthecaraccident.Philipcan(could)havebeenhurtseriouslyinthecaraccident.在疑問句中can/could表示對過去情況的疑問性推測，表示“可能已經了嗎？”。如：Someone must have broken into our b

18、edroom. Who could have done it?有人闖入了我的臥室。會是誰呢？Where was your sister then? 當時你姐姐在哪？She could have gone swimming with some friends.她可能和一些朋友游泳去了。2)cant / couldnt have done：表示對過去情況的否定性推測，表示“不可能已經做了某事”。如：I cant/couldnt have lost the key. I never drop things.我不可能把鑰匙丟了。我從來沒丟過東西。3)could + have done：表示本來能夠做卻

19、沒有做某事，是說話人責備的語氣。 might + have done也可表示某一事情在過去沒有實現并含有“勸告、責備”的意思。如：Oh,the train has left. You could have got up earlier.噢，火車已經開了。你本來可以早點起床啊。4)musthave+donesth，對過去時間里可能發生的事情的推測，語氣較強，具有肯定，想必的意思。-Lindahasgonetowork,butherbicycleisstillhere.-Shemusthavegonebybus.I must have seen you somewhere, but I cant

20、recollect your name.我一定在什么地方見過你，可是我想不起你的名字了。5)oughttohavedonesth / shouldhavedonesth本應該做某事，而事實上并沒有做。Yououghtto(should)havebeenmorecarefulinthisexperiment.shouldnt/oughtnt to + have done：否定句表示過去不該做某事卻已經做了的情況，也表示說話人后悔或責備的語氣。如：Heoughtnottohavethrowntheoldclothesaway.（事實上已扔了。）oughtto在語氣上比should要強。You sh

21、ouldnt have thrown all the books.你不該扔了全部的書。6)neednthavedonesth本沒必要做某事 You neednt have apologized to her. It was not your fault.你本不必向她道歉，那不是你的錯。Idressedverywarmlyforthetrip,butI neednthavedoneso.Theweatherwashot.7)wouldliketohavedonesth本打算做某事I would rather have come to help you with your English, but

22、 I was too busy at that time. 我本想來幫你學英語的，但是我當時太忙了。Iwouldliketohavereadthearticle,butIwasverybusythen.8) would rather have done：表示本來想做某事卻未做成的意思。如：I would rather have come to help you with your English, but I was too busy at that time. 我本想來幫你學英語的，但是我當時太忙了。9) need和dare這兩個詞既可以作情態動詞也可以作行為動詞，其用法區別如下：比較內容

23、是否有人稱和數的變化 是否有時態的變化 是否借助于助動詞搭配 行為動詞 有 有 是 + to do sth./sth. 情態動詞小練（二）1. I lived with my sister this summer and didnt have to pay rent. So I _ save most of my salary. A. was able to B. would C. must D. should2. I promised to get there before 5 oclock, but now the traffic is still so heavy. They _ for me impatiently. A. may wait B. must be waiting C. could wait D. ought to wait3. I _ her, but I never could. A. ought to help B. must help C. must have helped D. ought to have helpe