Model verbs 情态动词 情态动词本身有一定的词义,但需与动词原形一起使用, 给谓语动词增添情态色彩,表示说话人对有关行为或事物的态度和看法, 认为其可能,应该或必要等。 情态动词后面通常加动词原形。 A1 can and cannot 我们用 can 表示某人具备某种能力做某事。 如: I can play basketball. We can finish the work in 20 minutes. 其否定形式为 cannot 或 can’t . 如 : I cannot swim. I’m afraid I can’t think of more examples to support this argument. 疑问句中, 把 can 提到句首,将 can 与主语的位置对调。 Can you speak any foreigner languages ? Can you solve this Maths problem ? I’m sorry, I can’t A2 may and may not 在请求对方的许可,或是准许你做某事时, 常用情态动词 may 和 can. may 比较正式, can 较常用且更口语化一些。 如: May I leave work early today? — 我今天可以早点下班吗? ---Yes, you may — 你可以 No, you may not — 你不可以 Can I open a window ? — 我可以开扇窗吗? ---Yes, you can — 你可以 No, you can’t — 你不可以 You may / can use my dictionary. 你可以用我的词典。 You may not/ cannot use my computer. 你不可以用我的电脑。 A3 must and must not must 用以表示“必须做某事” 或“一定要做某事”, 具有强制性, 表达一种责任或义务或表示很有必要做某事; 或在提出建议时使用, 意为“应该; 得”。 如 : We must obey the school rules. The windows are very dirty. I must clean them. We must go to the bank today. We haven’t got any money. It’s a fantastic film. You must see it. must 的否定形式是 mustn’t, 表示“禁止”, “决不允许”,具有强制性。 如 : I must hurry, I mustn’t be late. You mustn’t forget to phone Julia. must 用于一般疑问句中,其肯定和否定回答应引起我们的注意。 Must I go now ? — 我们现在一定要走吗? — Yes, we must — 是的; 我们一定要走 No , we mustn’t — 不, 我们不可以走。 Must I finish reading the book this week ? --- Yes, you must No, you needn’t( 不必 ) 典型例析 ( ) 1. — _________ your American friend eat with chopsticks ? — Yes, but he can’t use them well. A. Can B. Should C. Must 【解析】 A 本句表示能力“ 会; 能够”, can 符合题意。 ( ) 2. Everyone ________ go through the security check ( 安检 ) when entering the World Expo Park. A. can B. may C. must D. ought 【解析】 C 本句表示“必须, 一定要”, must 符合题意。 ( ) 3. — The winners of the race is a tall and thin boy with glassed. —Then it _______ be my friend, Mike, who looks very fat. A. might B. can’t C. don’t D. Should 【解析】 B 由上下文语境可知本句的意思是“那么他不可能是我的朋友”, 表推测“不可能”“can’t” ( ) 4. — Must I go to the shop with you , Mum? Err... I can make it myself, Mike. You ______ go with me. A. mustn’t B. shouldn’t C. wouldn’t D. needn’t 【解析】 D 由上下文语境可知本句的意思是“ 你没必要去”, 表示“不必要” 可用 needn’t 或 don’t have to ( ) 5. — This desk is too heavy. I _______ move it. Could you help me ? — No problem A. can B. can’t C. should D. shouldn’t 【解析】B 句意为“这桌子太重, 我没法移动它。” 表示“没能力做某事”应用 can’t ( ) 6. — Must I finish my homework right now 、 No , you _________. A. needn’t B. may not C. mustn’t D. can’t 【解析】 A 此处must 提问表示“必须” , 否定回答只能用 needn’t 或 don’t have to . ( ) 7. — ________I take some photos in the hall ? No , you __________. A. Can; needn’t B. Must; mustn’t C. Could; won’t D. May; mustn’t 【解析】D 句意: “ 我可以在大厅里照相吗?” “ 不, 不可以”。 表示请求许可 can 或 may , 其否定回答用 can’t 或 mustn’t ( ) 8. — _________ I use your ruler, Lingling? Sure. Here you are. A. May B. Would C. Need D. Must 【解析】A 根据句意“用一下你的尺子可以吗?” 可知此处是表示请求许可, 可用may 和can. 语法专练 一 用 can , may 或 must 的适当形式填空。 1. __________ I ask you a question ? 2. Attending a ball ________ be exciting. 3. Michael _______ be a policeman, for he’s much too short. 4. — Are you coming to Jeff’s party? — I’m not sure. I _______ go to the concert instead. 5. He never takes a taxi. He _______ be very poor. 6. I thought you ________ like something to read, so I have brought you some books. 7. Look! I __________ stand on my hands. 8. He ______ have been to Shanghai. He knows so well about Shanghai. 9. The play is not interesting. I really _________ go now. 10. She______ like this place. 11. — Could I take this seat, sir? — Yes, you _________. 12. It ________ be very hot in Shengyang in summer. 13. I have just met her in the supermarket. She ______ be in Shanghai now. 14. ______ you be happy and healthy. 15.We _______ spit in public