2021屆高考英語一輪復習第二部分語法專項突破第二板塊專題三情態(tài)動詞學案新人教版

1、專題三情態(tài)動詞 知 識 梳 理 情態(tài)動詞本身有一定的詞義，但需和其他動詞一起構成謂語。除ought, used外，情態(tài)動詞后面接動詞原形。情態(tài)動詞中have to可以用have got to代替；need, dare也可用作實義動詞；used to有兩種否定形式：used not to和did not use to。can，could表示具有某種能力，指有能力做某事he could swim when he was five.by the age of seven he could write beautifully.表示請求和允許，和may相近；口語中可用could表示委婉語氣，但回答時仍用

2、cancould /can i use your pen?yes, of course you can.could i ask for your reaction to this policy？表示推測，常用于否定句和疑問句中mike cant have found his car, for he came to work by bus this morning. i think the work can be completed ahead of time.表示“有時也會”it can be quite windy there, especially in spring.cannot but

3、 do sth.表示“只好，不得不”father cannot but agree with his daughters opinion.cant help doing sth.表示“禁不住做某事”i cant help feeling sorry for the poor man.the film is so impressive that we cant help crying.be able tobe able to可以有多種時態(tài)，如：將來時(will be able to)，完成時(have /has /had been able to)i will be able to speak

4、french in another few months.i have been able to swim since i was 5.be able to側重通過努力成功做成某事的能力he said he could swim across the river. (指本身具有這種能力)at last he was able to swim across the river. (指通過努力做到了)may, might表示允許、許可或征求允許，否定回答時要用mustnt; might比may語氣委婉might /may i smoke in this room? no, you mustnt.m

5、ay /might i take this book out of the room? yes, you can. (no, you mustnt.)表示可能性，might比may可能性更小i think the trip may give me time to calm down.an active volcano may explode at any time.dont go too far afield or we might lose you.may /might as well do sth.“不妨做某事，還是做某事為好”everything is ready. we might a

6、s well start now.will，would表示意志、決心或愿望we will do our best to save the child.i told her to stop crying, but she just wouldnt listen.用于第二人稱，表示請求、建議等will /would you please post the letter for me?wont you take off your coat？will表示“總是，慣于”； would表示過去的習慣，意為“過去常?！眞hen he was a child, he would often go skiing

7、.he would sit there for hours sometimes doing nothing at all.表示推測或猜想this will be the house youre looking for.i think he would accept the invitation.shall用于第一、三人稱的疑問句中，表示征求對方的意見或請示shall i clean the desks one by one？用于第二、三人稱的陳述句，表示說話者的命令、警告、許諾等語氣he shall return that book tomorrow. (命令)i shall think it

8、 over and let you know my idea. (許諾)you shall fail if you dont work harder. (警告)用于第三人稱，在條約、規(guī)定、法令等文件中表示義務或規(guī)定，意為“應該，必須”candidates shall remain in their seats until all the papers have been collected.persons under 18 shall not be employed in night work.should, ought to表示“應該”，常用于表示現(xiàn)在或?qū)淼呢熑位蛄x務；還可表示推測，指有一

9、定依據(jù)的推測we should /ought to help each other and learn from each other in our work.we ought to go and see mary tomorrow, but i dont think we will.it ought to be a fine day tomorrow morning.should還可表示驚訝，意為“竟會，居然”its strange that he should be absent.it seems unfair that this should happen to me.must, hav

10、e tomust強調(diào)主觀看法，表示“必須”，have to強調(diào)客觀需要，意為“不得不”yesterday morning i told my father that i must call on a friend. you have to wear uniform on duty, dont you？must表示“偏要，非得”等含義，這種用法常用于疑問句、條件句中must you waste so much time?must you make so much noise? why must you always interrupt me? we were ready to leave, bu

11、t the baby must catch cold.mustnt意為“不許，禁止”；若表示“沒有必要，不必”時，用neednt或dont have tothat car is my property; you mustnt use it without my permission.you mustnt drive into a street with a “no entry” sign.you neednt talk to anyone if you dont want to.you dont have to worry about me. im a good swimmer.must表示推

12、測時，僅用于肯定句，但在反意疑問句中，其后面反問部分取決于must后面的動詞形式y(tǒng)ou must be a newcomer, arent you? she must have been very young when she got married.it must be your mother who you are thinking of.need表示“需要，必須”，常用于疑問句和否定句中； 肯定回答用must，否定回答用needntyou neednt have the bike repaired right away.need i go back to xiamen after i v

13、isited fuzhou? yes, you must. /no, you neednt.dare主要用于否定句、疑問句以及條件句中，有過去式形式dareddare she tell him what she thinks about him? she darent say anything. he will only shout at her. “how dare you speak to me like that？” he will say.used to“過去常?！?，含有今昔對比的意味，表示過去習慣的動作或狀態(tài)現(xiàn)在已結束，而would表示過去反復發(fā)生的動作，但不含對比意味he used

14、 to get up at six every morning. (現(xiàn)在不這樣了) he would get up at six every morning and had a walk in the forest then. (現(xiàn)在是否還這樣不得而知) had better，would betterhad better /would better表示“最好”(但一般都用had better)；would better還可表示“寧愿，寧可”you had better go to the factory and have a look. i would better die before as

15、king him for help.情態(tài)動詞havedonemust have done用在肯定句中，表示對過去情況的肯定推測，語氣堅定it must have rained last night, for the road is wet. tom must have taken your dictionary by mistake.cant have done表示對過去情況表示否定的推測，是must have done的否定形式mr.smith cant have gone to beijing, for i saw him in the library just now.mary cant

16、 have stolen your money. she has gone home.could have done用于肯定句，表示過去本能完成某事但事實上并沒有完成，意為“本來能夠做”he could have passed the exam, but he was too careless.he could have bought the car, but soon his company went bankrupt.may /might have done表示過去可能發(fā)生某事，意為“可能，或許”；might have done還可表示“本可能做某事”what has happened t

17、o george?i dont know. he may have got lost.she might have achieved greater progress, if you had given her more chances.should have done表示“過去本應該做某事而沒有做”tom, you are too lazy. the work should have been finished yesterday.if i knew she was short of money, i should have lent her some.shouldnt have done sth.表示“過去本不該做某事而實際上做了”look, tom is crying. i shou