必威体育精装版版钟萍-情态动词2012-2-19.ppt

Modal Verbs 情态动词 一、何谓“情态动词”？ 情态动词主要用来表示说话人的情感、态度等。 二、情态动词的特点 1.没有人称和数的变化(have to, have got to, be able to 除外) 2.有些情态动词有过去式的变化 e.g. will → would , can → could , may→ might ,? dare → dared 3. 情态动词本身具有一定词义,但不能单独做谓语, 后一般接动词原形一起构成谓语部分。 三、情态动词的否定形式 情态动词+ not +动词原形 can not: cant , must not: mustnt , need not : neednt 一. can , could和be able to 1.can 1)“能” , 表示能力、技能 We can speak two languages. A computer can’t think for itself.(不能) ★could 表 过去的能力 I could swim when I was only six. 表能力 ★be able to ① 表能力，可用于各种时态, You will be able to skate after practising it several times. He hasn’t been able to walk since his accident. ②还可表示成功地做了某事 = manage to do/succeed in doing sth. 此时只能用was/ were able to,不能用could The big fire spread quickly in the hotel but everyone was able to get out. 1.You don’t have to know the name of the author to find a book. You __ find the book by the title. must B. need C. can D. would 2.Just be patient. You___ expect the world to change so soon. can’t B. needn’t C. may not D. will not 2) “可以”，表示许可(和may意思相近)常见于口语 Can/May/Could (委婉语气)I come in? 我能进来吗? Can/May/Could (委婉语气) I smoke here? 我可以在这里抽烟吗？ ---Can/ May/ Could (委婉语气) I use your pen? ---Yes, you can. /you can (may) use my pen. Yes, you could. --- No, you can’t. 3) “有时可能” 在肯定句中，can可以表示一时的特定的可能性/ 表理论上的可能性 A clever person can make a mistake in his life. Children can be very naughty sometimes. It can be very hot in November in South China. 1. It is usually warm in my hometown in March, but it ___ be rather cold sometimes. A. must B. can C. should D. would 2. Peter __ be really difficult at times even though he’s a nice person in general. shall B. should C. can D. must 3.The World Wide Web is sometimes jokingly called the World Wide Wait because it ___ be very slow. A. should B. must C. will D. can 4) “可能”, 表推测/可能性,常用在疑问和否定句中 ◆can be “可能是…/可能在…” --Can the news be true? --It can’t be true. What can he possibly mean? He can’t be her father,