《情态动词详解》PPT课件.ppt

情态动词用法详解,情 态 动 词 的 定 义,情态动词是一种本身有一定的词义，表示说话人的情绪、态度或语气的动词，但不能单独作谓语，只能和其他动词原形构成谓语。 We can be there on time tomorrow. May I have your name? Shall we begin now? You must obey the school rules.,can / could,may / might,must,shall / should,will / would,need,dare,ought to,had better,cannot / could not,cant / couldnt, + not,maynt / mightnt, + not,mustnt, + not,shant / shouldnt, + not,wont / wouldnt, + not,neednt, + not,darent,ought not to,oughtnt to,Had better not,d better not,情 态 动 词 的 位 置,情态动词在句中放在谓语动词之前，谓语动词前若有助动词，则在助动词之前，疑问句中， 情态动词放在主语之前。 I can see you. Come here. 我能看见你，过来吧。 He must have been away. 他一定走了。 What can I do for you? 你要什么？ How dare you treat us like that! 你怎么敢那样对待我们!,情 态 动 词 的 特 点,情态动词无人称和数的变化，情态动词后面跟的动词需用原形，否定式构成是在情态动词后面加“not”。个别情态动词有现在式和过去式两种形式，过去式可以用来表达更加客气、委婉的语气，时态性不强，可用于过去，现在或将来。 He could be here soon. 他很快就来。 We cant carry the heavy box. Im sorry I cant help you. 对不起，我帮不上你。,情 态 动 词 的 用 法,、表能力 （can, could, be able to, were / was able to, could have done） 1. 表现在的或一般的能力：表示现在的或一般的能力用can 或 be able to. 一般的能力是指你无论什么时候做什么事情就能做到的能力。表示现在的能力或一般的能力时，can比be able to 更普遍。,、表能力 ：表现在的或一般的能力：表示现在的或一般的能力用can 或 be able to. 一般的能力是指你无论什么时候做什么事情就能做到的能力。表示现在的能力或一般的能力时，can比be able to 更普遍。 A computer cant think for itself; it must be told what to do. （表示一般的能力） I am starving to death. I can eat two bowls of rice now. （表示现在的能力）,2. 表示将来的能力 表示将来的能力用 will be able to. If you have a good sleep, you will be able to work out this problem. 3. 表示过去的能力 （1）could , was/ were able to 表示过去一般的能力，即不表示做与未做某事。 She could / was able to sing like an angel when she was a child.,3. 表示过去的能力 （1）could , was/ were able to 表示过去一般的能力，即不表示做与未做某事。 She could / was able to sing like an angel when she was a child. (2) was/ were able to 表示过去有能力并且成功地做了某事，相当于managed to do something / succeeded in doing sth. The fire spread through the hotel very quickly but everyone was able to get out. (过去有能力并成功地做了某事),(3) could have + 过去分词，表示过去有能力做但未做。 I could have worked out the problem, but I didnt.,二、表推测 。 可能性可分为客观的可能性和具体事情实际发生的可能性两种。 所谓客观的（理论的）可能性即不涉及具体某事是否发生，此种用法常常可以说明人或事物的特征。 情态动词 can 可用于肯定句中表示客观的 / 理论的可能性， 而表示具体事情发生的可能性时，can 一般不用于肯定句。 Accident can happen on such rainy days. （客观的可能性）,二、表推测 。 1. 可能性可分为客观的可能性和具体事情实际发生的可能性两种。所谓客观的（理论的）可能性即不涉及具体某事是否发生，此种用法常常可以说明人或事物的特征。情态动词 can 可用于肯定句中表示客观的 / 理论的可能性，而表示具体事情发生的可能性时，can 一般不用于肯定句。 Accident can happen on such rainy days. （客观的可能性） Peter may come with us tonight, but he isnt sure yet. （实际的可能性，不用 can,而用 may.,2. 表示具体事情实际发生的可能性 （1）表示具体事情实际发生的可能性的层次比较 （见下表） （2）表示具体事情实际发生的可能性时， may, must 常用于肯定句，一般不用于否定句和疑问句（may not表示“可能不”）； I didnt hear the phone. I must have been asleep.(表示肯定 ) This may not be done by him.（表示不确定）,表示具体事情实际发生的可能性时， can 常用于否定句、疑问句或感叹句中，表示疑惑、惊讶或不相信等意思；could 既可疑用于肯定句，又可以用于否定句、疑问句中。 This cant / couldnt be done by him. (表示不相信) He could be on his way home now. （could 不如 may / might常用） Can this be done by him? （表示一种疑惑、惊讶）,（3）would, could, should, might 并不一定与过去的时间有关，而是表示可能性弱于他们相应的现在形式。如： This may / might be done by him. （语气一次递减） 4）should 表示推测时，表示确定或可能有的未来或期望，即合乎理想的情况或结果。 He should be around sixty years old. 他可能60岁上下。 Its nearly seven oclock. Jack should be here at any moment. （表示确定或期待）,4）should 表示推测时，表示确定或可能有的未来或期望，即合乎理想的情况或结果。 He should be around sixty years old. 他可能60岁上下。 Its nearly seven oclock. Jack should be here at any moment. （表示确定或期待） - When can I come for the photos? I need them tomorrow afternoon. - They should be ready by 12:00. （表示期待）,三、 “情态动词 + have done “ 用法一览表 1. must have done 表示对过去已经发生的行为进行推测，意为“想必 / 准是/ 一定做了某事 It must have rained last night, for the road was quite muddy. The lights were out. They must have been asleep.,2. can have done cannot have done表示对过去发生的行为的怀疑和不肯定，通常用于否定句和疑问句中。 He cannot have forgotten it. Can he have gone to his aunts? 3. Could have done 可用于肯定句中，表示“可能已经”之意，此外，还可以表示过去免于是想的可能性，意为“本应该”.,3. Could have done 可用于肯定句中，表示“可能已经”之意，此外，还可以表示过去没有实现的可能性，意为“本应该”. I saw Mr. Wang just now. He couldnt have gone to Beijing. You could have been here earlier, but you didnt.,4. May /might have done 表示对过去已经发生的行为的推测，意为“也许 / 或许已经（没有） ”. 一般只用于肯定句或否定句中(在否定句中表示“可能不”)，不用于疑问句。用 might 语气更加不肯定。 Its too late. I think he may have gone to bed. He may not have finished the work. He might have caught a cold.,5. Might have done 表示“本来可能”，但实际上没有发生的事。 另外，还可以表示“本应该或可以做某事，”,含有轻微的责备语气。 You should not have swum in that sea. You might have been eaten by fish. You might have given him more help, though you were busy.,6. Should / ought to have done 用于肯定句时，表示“本应该做某事，而实际上未做”；用于否定句时，则表示 “不应该做的事情反而做了”。You should have come to the meeting earlier. You ought to have done this exercise more carefully. You shouldnt have told her the truth. He ought not to have treated his parents like that.,7. Neednt have done 表示“做了本来不必去做的事情”， 注意：didnt need to do 表示“没有必要做而实际也免于做某事”。 You neednt have taken a taxi here, for it was very near to my house. I didnt need to clean the windows. My brother did it.,8. Had better have done 用于事后的建议，含有轻微的责备语气，意为“当时做好做了某事”，其否定形式是 had better not have done 表示相反的意思。 You had better have started earlier. You had better not have scolded her.,9. Would rather have done 表示“当时宁愿做某事”，其否定式是 had better not have done. I would rather have taken his advice. I raised objections at the meeting, but now I would rather not have done that.,10. Would like / love to have done 表示过去愿意做某事，但未做成. I would love to have gone to the party last night but I had to work extra hours to finish a report.,情态动词其它用法要点 cannot but + do sth. 表示“不得不，只好”。如： I could not but choose to go. 我只好去。 2. May well 和 may as well 结构 “may well”意为 “完全能，很可能”，相当于 to be very likely to.如： He may well not recognize her because she has changed a lot.,情态动词其它用法要点 2. May well 和 may as well 结构 “may well”意为 “完全能，很可能”，相当于 to be very likely to.如： He may well not recognize her because she has changed a lot. “may as well + 动词原形”意为“最好，倒不如”，相当于 had better , 如： You may as well do it at once. We may as well stay where we are.,3. must 作“偏要、硬要”做某事。如: - How old are you, madam? - If you must know, Im twice my sons age.,4. may 作“可以”讲时，其否定式常用“mustnt表示被禁止”；must 作“必须”讲时，其否定形式是 “neednt”, 表示 “不必”。 - May I use your car? - No, you mustnt. (委婉的拒绝可以用: Sorry, I am suing it now. 或 Youd better not等),5. need 和 dare 的用法 两者既可以用作情态动词，又可以用作行为动词。作行为动词时，有人称和数的变化，而作情态动词时没有人称和数的变化（dare 可以有过去式 dared）,直接接动词原形，只用于疑问句和否定句中。,另外，dare 作为情态动词时，还可以用于条件句中，过去式为 dared; dare 用于疑问句和否定句，后面的to 也可以省略； I dare say 是习惯用法，意为“我想，大概”。,He neednt do it. He doesnt need to do it. I didnt know whether he dared say that to him. He didnt dare (to) do that. He dared not do that. 注意： need 作为行为动词时，还可以表示“需要”，后接动名词的主动式表示被动含义。,2. may (might) “可以”，表示说话人同意，许可或请求对方许可。 You may take the book home. 你可以把书带回家去。 May I come in? 我可以进来吗? May I use your dictionary? 我可以用你的词典吗? You may put on more clothes. 你可以多穿点衣服。 He said he might lend us some money. 他说他可以借给我们一些钱。 may 否定式为 may not, 缩写形式是 maynt。might 是may 的过去式，有两种用法，一种表示过去式，一种表示虚拟语气，使语气更加委婉、 客气或对可能性的怀疑。 He told me he might be here on time. 他说他能按时间来。 Might I borrow some money now? 我可以借点钱吗? He might be alive. 他可能还活着。,3. must “必须；应该；一定；准是”，表示说话人认为有必要做某事，命令、要求别人做某事以及对事物的推测。must 用来指一般现在时和一般将来时， 过去式可用 have to 的过去式代替。 I must finish my work today. 我今天必须完成我的工作。 You mustnt work all the time. 你不能老是工作。 Must I return the book tomorrow? 我必须明天还书吗? After such a long walk, you must be tired. 走了这么长的路, 你一定累了。 He must be the man I am looking for. 他一定是我要找的人。 He had to go because of somebodys calling him that day. 那天他要走，因为有人叫他。,值得注意的是： （1）must + have + 过去分词，表示现在对过去事物的推测。 He must have told my parents about it. 他一定把这件事情告诉我父母亲了。 He must have received my letter now. 他现在一定收到我的信了。 Its six oclock already, we must have been late again. 已经六点钟了，我们一定又迟到了。 （2）must 和 have to 的区别: must 表示说话人的主观思想, have to “不得不,必须”，表示客观需要、客观条件只能如此。 You must do it now. 你必需现在就干。(说话人认为必须现在干) I have to go now. 我得走了。(客观条件必须现在走) You must be here on time next time. 你下次一定要按时来。 I have to cook for my child. 我得给孩子做饭。,4. need “需要”，多用在否定式或疑问句中. Need I attend the meeting tomorrow? 我需要明天参加会议吗? You need not hand in the paper this week. 这一周你不必交论文。 need 是一个情态动词，他的用法完全和其他情态动词一样，但 need 还可当作实义动词使用，这时 need 就象其他动词一样，有第三人称，单复数， 后面加带 to 的动词等特性。 I need a bike to go to school. 我上学需要一辆自行车。 Do you need a dictionary? 你需要词典吗? She needs a necklace. 她需要一条项链。 注意：“neednt + have + 过去分词” 表示过去做了没必要做的事情。 You neednt have taken it seriously. 这件事情你不必太认真。,5. dare “敢”，多用在否定或疑问句中。 The little girl dare not speak in public. 小女孩不敢在公众面前说话。 Dare you catch the little cat? 你敢抓小猫吗? dare 除用作情态动词外，更多的是当实义动词使用， 用法同实义动词一样，要考虑人称，单复数，时态等。 Do you dare to walk in the dark? 你敢黑夜走路吗？ He doesnt dare to tell the teacher what happened that day. 他不敢告诉老师那天发生的事。,6. ought “应当；应该”，后面跟带有 to 的动词不定式。 You ought to read these books if you want to know how to repair the motorcar. 如果你想知道如何修理汽车,你应该读这些书。 You ought to bring the child here. 你应该把孩子带来。,ought + to have done 句型。指过去动作,表示一件事情该做而未做。 You ought to have been here yesterday. 你昨天就应该来。 ought not to have done 句型。表示一件不该做的事情却做了。 You ought not to have taken the book out of the reading-room. 你不应该把书带出阅览室。,7. will (would) 表决心、愿望。 would 为 will 的过去式, 可用于各人称。 Ill do my best to catch up with them. 我要尽全力赶上他们。 Ill never do it again, thats the last time. 我再不会做那件事情了,这是最后一次。 He said he would help me. 他说他会帮助我。 will, would用于疑问句表示说话人向对方提出请求或询问,用 would 比 will 更婉转,客气。 Its hot. Will you open the windows? 天气太热了,你能打开窗户吗? Will you help me to work it out? 你能帮我解这道题吗? Would you like some coffee？ 给你来点咖啡怎样？,8. shall, should 表示命令, 警告, 允诺, 征求, 劝告, 建议, 惊奇。 You should hand in the exercise book. 你应该交作业本儿了。 This should be no problem. 这应该没问题。 Shall we go now? 我们现在可以走了吗? Why should I meet him？ 为什么我要见他?,情态动词专练题,1.Put on more clothes. You be feeling cold with only a shirt on. A. can B. could C. must D. would 2. Must I drive to his house and pick up the children? No, _. A. you shouldnt B. you might not C. you neednt D. you mustnt 3.You to attend the meeting, but you didnt. A. should come B. would have come C. came D. should have come 4.We didnt see Tom at the meeting yesterday. He it. A. mustnt have attended B. cannot have attended C. neednt have attended D. would have not attended 5.Tom went on foot, but he by bus. A. might go B. may go C. could have gone D. ought have gone,6.We play chess than bridge. Some of us dont know how to play bridge. A. had better B. would better C. would rather D. had rather 7.There is someone knocking at the door. it be Tom? A. Can B. Must C. Should D. Ought 8.There was a lot of time. He . A. mustnt have hurried B. neednt have hurried C. could have hurried D. ought to have hurried 9.“We didnt study Chemistry last night, but we .“ A. had studied B. could C. should D. could have 10.One ought for what one hasnt done. A. not to be punished B. to not be punished C. to not punished D. not be punished,11.“May I pick a flower in the garden?“ “ .“ A. No, you neednt B. Not, please C. No, you mustnt D. No, you wont 12.“Could I call you by your first name?“ “Yes, you .“ A. will B. could C. may D. might 13.Two years ago, my husband bought me a bicycle. If you live in town, it is often faster than a car and you worry about parking. A. must not B. may not C. should not D. dont have to 14.I didnt see her in the meeting-room this morning. She at the meeting. A. mustnt have spoken B. shouldnt have spoken C. neednt have spoken D. couldnt have spoken 15.I wonder how he that to the teacher. A. dare to say B. dare saying C. not dare say D. dared say,16.You take your umbrella. I am sure it wont rain. A. shouldnt B. cant C. dont have to D. mustnt 17.The dog hibernate in winter. A. dont need B. doesnt need to C. needs not to D. needs not 18.Look what you have done. You have been careful. A. should B. can C. must D. may 19.Tom did not go to the party yesterday, or I him. A. would see B. could meet C. might have seen D. might see 20. Lets go to the cinema, shall we? ? A. No, I cant B. Yes, I will C. Yes, thank you D. No, w