Grammar: Modal verbs 语法特征 ? 情态动词有一定的意义 ? 无人称和数的变化 ? 通常不带to ? 表示说话人的语气或情绪 1.Ability (能力): Liu Xiang can run the 110m hurdle race within 13 seconds. can/could: 1. can 一般表示与生俱来的能力或 者一种客观可能性,还可以表示请 求和允许 。 Man can not live without air. Learning English _____ can be difficult. Can _______ I use your bike? can/could: 2.在疑问句中,用could可表示请 求,语气较委婉。 He asks if he could ____ smoke here. — Could ____I have the television on? can/may — Yes, you _____. / No, you _____ can’t/I’m afraid not can/could: 3.表示惊异、怀疑、不相信的态度。(主 要用在否定句、疑问句或惊叹句中) Can this be true? He’s such a nice person that can’t commit the crime. he ______ How can you be so careless! 你怎么会如此地粗心! can/could: 4. can never/can’t……too表示 “无论怎样…也不过分”,“越…越 好” 。 You can’t be too careful 你过马路的时候再小心也不为过。 while crossing the road. can/be able to区别: Edison always wondered why hens could hatch (孵) chickens while he was not able to. Question: Are the two modal verbs interchangeable (互换) ? If not, why? can表示与生俱来的能力或一种客观可能,而 be able to更加强调通过后天的学习和努力获 得的能力,或者在某个客观的场合和背景下, 能做到的事情。 Sum up 1. can 和 be able to 1) can (could) 表示能力、可能, 只用于 现在时和过去时。 2) be able to可以用于各种时态。 只用be able to的情况: a. 位于助动词后。 b. 情态动词后。 c. 表示过去成功地做了某事时,只能用 was/ were able to,不能用could。 can/be able to区别: 1.A big fire broke out in ABC hotel yesterday. Luckily, everyone was able to run out of __________ the building. 2. She speak both English and French. can _____ 1. They will ______ D run this machine on their own in three months. A. can B. could C. may D. be able to A seat 2,000 2. That big cinema ______ people. A. can B. should C. ought to D. is able to 3.(2007福建) My MP4 player isn’t in my bag.Where ___I A have put it? A. can B. must C. should D. would 4. A left-luggage office is a place where bags ____be B left for a short time, especially at a railway station. A. should B. can C. must D. will A you say that you 5. How ___ really understand the whole story if you have covered only part of the article? A. can B. must C. need D. may B be a policeman, for 6. Mike ___ he is much too short. A. needn’t B. can’t C. should last winter. D. may 7. — I heard they went skiing in the mountains — It ____ true because there was little snow there. C A. may not be B. won’t be C. couldn’t be D. mustn’t be 2.Obligation (义务): I’m so tired! I have to do the training for at least 10 hours a day! Although Liu Xiang is so gifted in hurdle race… …yet he must work hard to win the gold medal. advisability ought to/should have to necessity must Your mother brings you up and takes good care of you, so when she is old, you ___ look after her in return. A. can B. may C. have to D. must 3.Certainty (可能性) : Although the chance of winning a medal is small, I’ll try my best! Shi Dongpeng might win a medal at the Olympic Games. very uncertain might may could (can) should almost certain ought to will must 1.He _____ be at home. A.may B.might C.must 2.He _____ be at home, for he just called me from his home 15 seconds ago. A.may B.might C.must must 1. must 表示肯定的猜测,译为“一定”, 不能用于否定句或疑问句。 This must be your pen. He must be doing his homework now. He must have arrived already. 2. 表示“坚持”(常用于固定句型:if you must do sth. 如果你非得要做某事) 如果你真的要走,那就悄悄离开。 If you must leave, do it quietly. 4.Permission (允许): May I eat KFC if I win the gold medal? may/might: 1. 表示许可。表示请求、允许时, might比may的语气更委婉一些。 — Might/May I use your computer? — Yes, you can. /No, you can’t/mustn’t. may/might: 2.用于祈使句中表示祝愿。 May you be happy all your life. May you succeed. 祝你成功! 3.表示推测、可能(只用于肯定句, 疑问句则要用can或could)。 He may be very busy now. 2) 成语:may/might as well,后面接 不带to 的不定式,意为"不妨"。 e.g. If that is the case, we may as well try. 5.Making requests (提出要求): informal will can could formal would I don’t know how to use this equipment! Can you help me with my training? 6.Making suggestions (提出建议): It’s too hot to take exercise in the afternoon. Shall we do the training in the morning? shall: 1.Shall