情態(tài)動(dòng)詞辨析.doc

情態(tài)動(dòng)詞辨析 情態(tài)動(dòng)詞有can (could), may (might), must, have to, shall (should), will (would), dare (dared), need (needed), ought to等。 情態(tài)動(dòng)詞無人稱和數(shù)的變化；不能單獨(dú)使用，必須與其后的動(dòng)詞原形構(gòu)成謂語一、 can, could1) 表示能力（體力、知識(shí)、技能）。Can you lift this heavy box?（體力）Mary can speak three languages.（知識(shí)）Can you skate?（技能）此時(shí)可用be able to代替。Can只有一般現(xiàn)在時(shí)和一般過去式；而be able to則有更多的時(shí)態(tài)。Ill not be able to come this afternoon.當(dāng)表示“經(jīng)過努力才得以做成功某事”時(shí)應(yīng)用be able to，不能用Can。如：He was able to go to the party yesterday evening in spite of the heavy rain.2) 表示請(qǐng)求和允許。-Can I go now? - Yes, you can. / No, you cant. 此時(shí)可與may互換。在疑問句中還可用could, might代替，不是過去式，只是語氣更委婉，不能用于肯定句和答語中。- Could I come to see you tomorrow? - Yes, you can. ( No, Im afraid not. )3) 表示客觀可能性（客觀原因形成的能力）。Theyve changed the timetable, so we can go by bus instead.This hall can hold 500 people at least. 4) 表示推測(cè)（驚訝、懷疑、不相信的態(tài)度），用于疑問句、否定句和感嘆句中。Can this be true?This cant be done by him.How can this be true?二、 may, might 1) 表示請(qǐng)求和允許。might比 may語氣更委婉，而不是過去式。否定回答時(shí)可用cant或mustnt，表示“不可以，禁止”。-Might/ May I smoke in this room? - No, you mustnt.- May/Might I take this book out of the room?- Yes, you can. (No, you cant / mustnt. )用May I.？征徇對(duì)方許可時(shí)比較正式和客氣，而用Can I.？在口語中更常見。2）用于祈使句，表示祝愿。May you succeed!3) 表示推測(cè)、可能性（不用于疑問句）。might不是過去式，它所表示的可能性比may小。1He may /might be very busy now.2Your mother may /might not know the truth.三、 must, have to1) 表示必須、必要。You must come in time.在回答引出的問句時(shí)，如果是否定的，不能用mustnt（禁止，不準(zhǔn)），而用neednt, dont have to（不必）.- Must we hand in our exercise books today?- Yes, you must.- No, you dont have to / you neednt.2) must是說話人的主觀看法， 而have to則強(qiáng)調(diào)客觀需要。Must只有一般現(xiàn)在時(shí)， have to 有更多的時(shí)態(tài)形式。His play isnt interesting, and I really must go now.I had to work when I was your age.3) 表示推測(cè)、可能性（只用于肯定的陳述句）1 Youre Toms good friend, so you must know what he likes best. Your mother must be waiting for you now.dare, need1) dare作情態(tài)動(dòng)詞用時(shí), 常用于疑問句、否定句和條件從句中, 過去式形式為dared。How dare you say Im unfair?He darent speak English before such a crowd, dare he?If we dared not go there that day， we couldnt get the beautiful flowers.2) need 作情態(tài)動(dòng)詞用時(shí), 常用于疑問句、否定句。在肯定句中一般用must, have to, ought to, should代替。1You neednt come so early.2. - Need I finish the work today? - Yes, you must. / No, you neednt.3) dare和 need作實(shí)義動(dòng)詞用時(shí)， 有人稱、時(shí)態(tài)和數(shù)的變化。在肯定句中，dare后面常接帶to的不定式。在疑問句和否定句中，dare后面可接帶to或不帶to的不定式。而need后面只能接帶to的不定式。1. I dare to swim across this river.2. He doesnt dare (to) answer.3. He needs to finish his homework today. 五、 shall, shouldshall的用法：1. shall表義務(wù)，用于第二、第三人稱。如：You shall do as you see me do. 你照我的樣子辦。He shall be punished if he disobeys. 他若不服從就要受到處罰。在當(dāng)代英語中，shall多用于正式法律文字。如：The vendor shall maintain the equipment in good repair.賣方須完好地維護(hù)設(shè)備。shall有時(shí)在從句中相當(dāng)于must。如：It has been decided that the proposal shall not be opposed.已經(jīng)決定不得反對(duì)這項(xiàng)提議。2. shall表許諾，用于第二、第三人稱，用于肯定句和否定句。如：You shall have my answer tomorrow. 你明天可以得到我的答復(fù)。She shall get her share. 她可以得到她的一份。3. shall表征詢意見，用于第一、第三人稱，并用于疑問句。如：Shall I get you some coffee, Miss Fleure?費(fèi)勒小姐，我給您點(diǎn)兒咖啡好嗎？What shall he do next? 他下一步干什么呢？should的用法：1. 用于第一人稱疑問句，表征詢意見。如：Should I open the window? 我可以開窗戶嗎？2. should表義務(wù)，可用于各種句式，通常指將來。如：You should do what your parents tell you. 你應(yīng)該照你父母的話去做事。He should do some work, but he doesnt want to.他應(yīng)該做些工作，但是他不想做。也可指現(xiàn)在。如：You shouldnt feel so unhappy over suchtrifles.對(duì)這種小事，你不應(yīng)該感到這么不高興。You shouldnt be sitting in the sun. 你不應(yīng)該坐在陽光下。3. should表推測(cè)，暗含很大的可能。如：Its 4:30. They should be in New York by now.現(xiàn)在是四點(diǎn)半，他們應(yīng)該到達(dá)紐約了。Three weeks should suffice. 三個(gè)星期應(yīng)該足夠了。4. should可在某些從句中，表虛擬語氣。如：I suggest that you should stay here as if nothing had happened.我建議你應(yīng)該待在這兒，好像什么事也沒有發(fā)生。She was terrified lest they should go on talking about her.她感到害怕，唯恐他們?cè)僬f她的事。If he should drop in, give him my message.他若來訪，就將我的消息給他。5. should表感情色彩，常用在以why, how開頭的疑問句中。如：Why shouldnt you invite him? 為什么你不邀請(qǐng)他？I dont see why we shouldnt make friends.我不明白為什么我們竟不能成為朋友。How should I know? 我怎么知道？在that引導(dǎo)的從句中，should也可表惋惜、憂慮、歡樂、驚訝等感情色彩。如：Im sorry that you should think so badly of me.你竟把我想得這樣壞，我感到遺憾。It is absurd that such things should happen to a family like theirs.真可笑，這種事竟發(fā)生在他們那樣的家庭中。should還用于一些特殊結(jié)構(gòu)，表感情色彩。如：That it should come to this! 事情竟到了這種地步！To think that it should have happened to me! 誰想到這種事竟發(fā)生在我身上！(2012重慶卷24) “The interest _be divided into five parts，according to the agreement made by both sides，”declared the judge Amay Bshould Cmust Dshall 【答案及解析】 D 由declared the judge可知，前面的話是法官的判詞，必須強(qiáng)制執(zhí)行。shall用于第二、第三人稱時(shí)，表義務(wù)、強(qiáng)制，而其它三個(gè)選項(xiàng)無此義。(2012北京春季卷21) -The room is so dirty_we clean it? -0f course AWill BShall CWould DDo 【答案及解析】B shall用于一般疑問句中，主語常用第一、第三人稱，表示征求對(duì)方意見或請(qǐng)求允許；而will和would在疑問句中，主語常用第二人稱。譯文：-房間如此臟亂。我們打掃一下好嗎?-當(dāng)然可以。(2012上海卷27) It has been announced that candidates _remain in their seats until all the papers have been collected A. can Bwill Cmay Dshall 【答案及解析】D shall用于陳述句的第二、第三人稱時(shí)，表示說話人的意圖、允諾、警告、命令、決心等，意思是“必須，應(yīng)，可”。譯文：據(jù)宣布，考生在收卷前必須坐在自己的座位上。(2012全國(guó)卷33) I was really anxious about you. You _ home without a word. A. mustnt leave B. shouldnt have left C. couldnt have left D. neednt leave 【答案及解析】B 表示原本不應(yīng)該做某事，含責(zé)備之意。If I _ meet Alan or his sister, Ill tell them about the terrible accident. A: will B: can C: shall D: should 【答案及解析】D 這里表示假設(shè)萬一的意思，譯文：萬一我遇到Alan或他姐姐，我就告訴他們這可怕的事故六、 will, would1) 表示請(qǐng)求、建議等，would更委婉。Will / Would you pass me the ball, please?2) 表示意志、愿望和決心。1. I will never do that again.2. They asked him if he would go abroad. 3) would表示過去反復(fù)發(fā)生的動(dòng)作或某種傾向。would表示過去習(xí)慣時(shí)比used to正式，且沒有“現(xiàn)已無此習(xí)慣”的含義。1. During the vacation, he would visit me every other day.2. The wound would not heal.4) 表示估計(jì)和猜想。 It would be about ten oclock when she left home.七、 should, ought to1) should, ought to表示“應(yīng)該”，ought to表示義務(wù)或責(zé)任，比should語氣重。1. I should help her because she is in trouble.2. You ought to take care of the baby.2) 表示勸告、建議和命令。should, ought to可通用，但在疑問句中常用should。1. You should / ought to go to class right away.2. Should I open the window?3) 表示推測(cè)should , ought to (客觀推測(cè)), must(主觀推測(cè))。1.He must be home by now. (斷定他已到家)2.He ought to/should be home by now.(不太肯定)3. This is where the oil must be.(直爽)4. This is where the oil ought to/should be.(含蓄)情態(tài)動(dòng)詞+have+done是歷年高考的重點(diǎn)和難點(diǎn)之一，現(xiàn)將其用法總結(jié)歸納如下：一、 “must+have+done”表示對(duì)過去事情的肯定推測(cè)，譯成“一定做過某事”，該結(jié)構(gòu)只用于肯定句。 1. It must have rained last night, for the ground is wet. 昨晚一定下雨了，因?yàn)榈孛孢€是濕的。2. You must have been mad to speak to the servant. 你和仆人說話，一定是發(fā)瘋了。二、 “cant+have+done”表示對(duì)過去事情的否定推測(cè)，譯成“不可能做過某事”。1. Mr. Smith cant have gone to Beijing, for I saw him in the library just now. 史密斯先生不可能去北京了，我剛才還在圖書館見過他。2. Mary cant have stolen your money. She has gone home. 瑪麗不可能偷你的錢，她回家去了。三、 “can+have+done”表示對(duì)過去行為的懷疑，用于疑問句，譯成“可能做過嗎？”。1. There is no light in the room. Can they have gone out? 屋里沒有燈，他們可能出去了嗎？2. There is nowhere to find them. Where can they have gone? 到處找不到他們，他們可能到什么地方去呢？四、 “could+have+done”是虛擬語氣，表示對(duì)過去事情的假設(shè)，意思是本來能夠做某事而沒有做。He could have passed the exam, but he was too careless. 本來他能夠通過考試，但是他太粗心。五、 “may+have+done”表示對(duì)發(fā)生過的事情的推測(cè)，意思是“可能已經(jīng)”或“也許已經(jīng)”，用于肯定句中。 What has happened to George?I dont know. He may have got lost.喬治發(fā)生了什么事？我不知道，他可能迷路了。六、 “might+have+done”表示對(duì)過去事情的推測(cè)，might與may意思相同，但可能性更小。多用于虛擬語氣結(jié)構(gòu)中。 1. He might have given you more help, even though he was busy. (MET90) 他或許會(huì)多給你一些幫助，即使他很忙。2. She might have achieved greater progress, if you had given her more chances. 如果你多給她點(diǎn)機(jī)會(huì)，她可能已經(jīng)取得更大的成績(jī)。七、 “would+have+done”虛擬語氣，表示對(duì)過去事情的假設(shè)，意思是“本來會(huì)做”。1. I would have told you all about the boys story, but you didnt ask me. 我本來會(huì)告訴你