情态动词的讲解.ppt

情态动词 概说： 情态动词表示说话人的语气和情态，需要，可能，愿意和怀疑等。情态动词有一定的词义，但不完整，必须和主要动词的原形一起构成谓语。常用的情态动词有：can, could, may, might, must, have to, ought to, need, dare, shall, will, should, would, be able to, etc. 一. can , could, be able to I. 1) can 表示体力或脑力方面的能力，或根据客观条件能够做某事的能力。 A blind man can not judge color. He can speak five languages. 2) 表示许可，在疑问句中表示要求，否定句中 表示不许。 Can (May) I come in ? ----- Can I use your dictionary? ----- Of course, you can. This kind of thing can’t go on. 3) 表示可能性，常用于疑问句和否定句中，指“某事是否是事实”。 Can it be true? Can the hall seat a thousand people? Someone is knocking at the door. Who can it be? She can’t be here. He can’t be serious. Mary can’t have gone there alone. 4) 表示温和的命令或批评 You can go and fetch some water. You can clean the windows first. You could read more in future. You could be more careful. 5) be able to与can 的比较 A) 表示能力时可通用 No one can / is able to do it. Can you come tonight? /Will you be able to come tonight? B) be able to可用于任何时态， can只能用在现在时或过去时（ could ）中。 I’m sorry I haven’t been able to answer your letter. He says / said he will / would be able to come home for Christmas. C) 表示经过努而成功地办到了某个具体的事情时，只能用be able to 不可用 can。 With the help of the firemen, they were able to leave the burning house. After years of hard work he was able to win the prize 2. could 1) could 是can的过去时，除具有can的各种功能外，还可以用来比较委婉，客气地提出问题或陈述看法。 Could you come a little earlier? I’m sorry I couldn’t lend you the book now. --- Could I borrow your bicycle? --- Yes, of course, you can. ( 不可用could ) I could come earlier, if necessary. 2) can 和could 还可表示某人或某物一时的特点，可译为“有可能，有时会”。 He can be very friendly. He could be very proud. Man can be as cruel as wild beasts. Children could be very trying. (伤脑筋) 二. may, might 1） 表示许可，允许，译为“可以”（正式场合） You may take the book home. People may not pick flowers in the park. I’d like to ask a question if I may ask. --- May I watch TV tonight? ---Yes, you may. (No