英语语法：情态动词用法总结ppt课件.pptx

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1、情态动词的基本用法,常见的情态动词：,Can(could)may(might)/will(would)mustneedoughtdare,一.Can ,could,1)表示能力(能力，体积，技能）e.g. Amy can skate. 注意:此时可用be able to代替。Can只有一般现在时和一般过去式；而be able to则有更多的时态。当表示“经过努力才得以做成功某事”时应用be able to，不能用Cane.g. He was able to go to the party yesterday evening in spite of the heavy rain.2）表示请求和允

2、许。e.g. Can I go now?Yes, you can. / No, you cant. 注意：此时可与may互换。在疑问句中还可用could , might代替，不是过去式，只是语气更委婉，不能用于肯定句和答语中。e.g.Could I come to see you tomorrow?- Yes, you can.No, Im afraid not.,3) 表示客观可能性（客观原因形成的能力）。,e.g. This hall can hold 500 people at least.4) 表示推测（惊讶、怀疑、不相信的态度），用于疑问句、否定句和感叹句中。e.g. Can thi

3、s be true? This cant be done by him.,二、 may, might,1) 表示请求和允许。might比 may语气更委婉，而不是过去式。否定回答时可用cant或mustnt，表示“不可以，禁止” e.g. Might/ May I smoke in this room?- No, you mustnt.注意：用May I.？征徇对方许可时比较正式和客气，而用Can I.？在口语中更常见2)用于祈使句，表示祝愿。e.g. May you succeed!3) 表示推测、可能性（不用于疑问句）。might不是过去式，它所表示的可能性比may小。e.g. He ma

4、y /might be very busy now.,三、 must, have to,1）表示必须、必要。e.g. You must come in time.注意：在回答引出的问句时，如果是否定的，不能用mustnt（禁止，不准），而用neednt, dont have to（不必）. e.g. Must we hand in our exercise books today? - Yes, you must. - No, you dont have to / you neednt.,2) must是说话人的主观看法， 而have to则强调客观需要。must只有一般现在时， have t

5、o 有更多的形式。E.g. I had to work when I was your age.,3)表示推测、可能性（只用于肯定的陈述句）e.g. Your mother must be waiting for you now.,四. shall, should,1）shall 用于第一人称，征求对方的意见。e.g. What shall we do this evening?2) shall 用于第二、三人称，表示说话人给对方的命令、警告、允诺或威胁。e.g. You shall fail if you dont work hard.(警告) He shall have the book

6、when I finish it.(允诺) He shall be punished.(威胁),五. will ,would 的用法,1. 表“意志”、“意愿”,用于各种人称.E.g. I will do anything for you.,2. 用于第二人称的疑问句中, 表示询问对方的意愿或向对方提出请求.E.g. Will you do me a favour to carry the suitcase upstairs?请你帮我把手提箱搬到楼上好吗？,Will的用法,3.表示习惯性的动作,有“总是”、“惯于”的意思.E.g. Man will die without water or a

7、ir.,.4. will do 表“够了”、“适合”、“行”等意思 .E.g.Must I come here this Saturday? If you are busy that day, Sunday will do.,1. 表过去的意愿.E.g. Though he would go to the south, his parents wouldnt let him.尽管他要去南方，他的父母却不让他去。,2. 表说话人的意愿或向对方提出请求,比 will 客气.E.g. Would you please say that again?,would 的用法,3. 表过去的习惯动作.E.g

8、. Whenever I passed his house I would see him standing under the big tree.每当我经过他的房子时，我都会看到他站在那棵大树下。,4.“would like to +动词原形” 意为“愿意”.E.g. Would you like to have a talk with me?,1. 表义务或强烈的劝告,意为“必须”、“应该”,否定式表示“禁止”、“不准”.在回答 must 的问句时, 否定回答用 neednt 或 dont have to .,E.g. You must finish your homework first

9、. Must I do it now? No, you neednt.,六、must,2. 对现在情况的猜测用“must + 动词原形”.E.g. You must be very tired now.,3. 对过去情况的猜测用“must+have +过去分词”.E.g. He must have been to Shanghai.,七、ought to,1. ought to =“should + 动词原形”,表“义务”、“劝告”.但语气比其强.E.g. You ought to take care of him.,2. “ought to + have + 过去分词” 表示过去应该做而未做

10、的事情.E.g. You ought to have helped him. (but you didn,八、 dare ,need,1. dare 和 need 都既有情态动词的功能,也有实义动词的功能. dare 用情态动词时常用于否定句、疑问句、和条件句中；need 作情态动词时用于否定句或疑问句中.,E.g. I wonder how he dared say that to the teacher. Shall I tell John about it? No, you neednt. I have told him already.,2.need 构成一般疑问句时,其肯定回答用mu

11、st ,否定回答用 neednt .E.g. Need I do it now? Yes, you must. (NO, you neednt.),3.“need (not) +have +过去分词”表示“本有（无）必要做某事,然而做了（没有做）”E.g. You neednt have told him about the news. He had known it long before.,情态动词在虚拟语气中的运用:,虚拟语气是谓语动词的一种特殊形式，用来表达假设、主观愿望、猜测、建议、可能或空想等非真实情况。,一.“情态动词+have done”,E.g. You could have

12、 passed my examination easily，but you made too many stupid mistakes.你本来是能轻易通过考试的，但你出了很多愚蠢的错误。（实际上考试不及格） E.g. He might have given you more help，even though he was very busy.即便他当时很忙，本来也是可以多给你一些帮助的。（实际上没给你更多的帮助）,1.could/may/might have done：本来可以做到、实际上没做到，经常带有责备或遗憾的意味,E.g. You should have finished your h

13、omework. （实际上没完成作业） E.g. I ought to have listened to your advice. （实际上没听从建议）,2.should/ought to have done本来应该做、但实际上没做。,E.g. He shouldnt have thrown the old clothes away. 他不该把旧衣服扔了。（实际上已扔）,3.shouldnt/oughtnt to have done本来不该做、实际上做了，常带有责备、自责的意味,E.g. He need have hurried to the station. In that case, he

14、 wouldnt have missed the train.他本来需要快点去车站，那样的话，他就不会误了火车。,4.need have done 本来需要做某事而没有做。,E.g. There was plenty of time. She neednt have hurried. 时间足够了；她本没必 要那么匆忙。 E.g. We neednt have bought so much food now that Suzie wont be with us for dinner. 既然Suzie不跟我们一起吃饭，我们本没必要买那么多东西。,5. neednt have done （通常用于否

15、定句）本不必做、实际上做了。,e.g. I would have told you all about the boys story, but you didnt ask me. 我本来会告诉你这个小男孩的故事，但是你没有问我。,6.would have done 本来会做,E.g. I would like to have read the article, but I was very busy then.,7.would like to have done 本打算做某事但没做,E.g. Its wonderful that you should have achieved so much

16、 in these years.这些年你竟然能取得如此大的成就，太棒了。（惊讶、赞美） E.g. It was sad to me that they， so poor themselves， should bring me food.他们自己很贫穷却给竟然给我带来了食物，我很难过。,二【补充】用于从句中，表示惊讶、奇怪、不快、赞美等感情：“竟然、竟会”，此时，既可以用完成式should have done，也可以用一般式should do。,三虚拟语气在条件句中的用法（复习）,e.g. If Iwereyou ，I would not go. 我要是你。我就不会去 e.g. Without your assistance ，we wouldnt have succeeded. 如果没有你的帮助，我们不会成功的。e.g. If it were to rain tomorrow, the meeting would be put off. (对将来的虚拟),