情态动词解读.pptVIP

can和could (1) 表能力（ability），“能，会” She can speak English. She could play the piano at the age of three. (2) 表请求（request）和许可（permission)，“可以”，could比can更加委婉，表示礼貌 Can I smoke here? —Could I use your computer? —Yes, you can. (3) can表客观可能性(possibility)，“有时候会”，用于肯定句 A wise man can sometimes make a mistake. (4) can表推测，用于疑问句、否定句。肯定句用must Can the news be true? He can’t be at home because I saw him here just now. can/ be able to 1.. be able to能用于各种时态；can/could只能表示现在或过去的能力。 2.was/were able to“设法做成某事”相当于managed to do sth// succeeded in doing sth All the people trapped in the burning house were able to get out of it. 3.Can的主语是人或物,be able to的主语是人 This machine can make you feel comfortable. She can/was able to sing the song in English. may和might 1. 表示允许、许可 —May I leave now? —No, you mustn’t. //Yes, you may. 2. 表示推测、可能，用于肯定句和否定句，might比may可能性更小 Nobody has ever seen him since that year. He may/might have gone abroad. 3. May + 主语 + 动词原形，表示祝愿 May you succeed. must和have?to 1. must表示出于主观意识而必须要做某事；have to却表示由于某种客观原因而不得不做某事。have to自身有时态的变化形式。 —Must we hand in our exercises today? —Yes, you must. /—No, you needn’t/don’t have to. 2. mustn’t意为“不应该，禁止” 3. must还可用来表示把握较大的推测，“一定”，其否定形式为can not/can’t（不可能） You must be tired after your long journey. 4. must 还表示“非得…, 一定 , 偏要” Must you make so much noise? After I gave her my advice，she must go and do the opposite. 5.must可表示“偏偏” 某事发生得不早不迟，就在某个当紧的时候，多指不受欢迎的事情的发生。 The car must break down just when we were starting our holidays. 正当我忙碌的时候，邻居偏偏过来聊天。 Just when I was busy, the neighbor must come and chat with me. will和would 1. 表示意愿、意志 If you will help me with my English, I will be very happy. 2. 在疑问句中，用于第二人称，表示请求或征求意见，would比will语气更委婉 Will/Would you please give me a hand? 3. 表示习惯性的动作，“总是，常常” He is strange. He will sit for hours saying nothing. My mother would read me a story every night . Fish will die out of water. Water will boil at 100 degrees centigrade. The door won’t open. 对比would和used to 1. 表示今昔动作对