1、情态动词.can 的用法：一、简介1、结构：can + 动词原形，没有人称和数的变化。2、否定形式：cannot/can t, cannot比缩略形式can t要正式。口语中一般用缩略形式。例如：I can swim.Daming can ride a bike. He cant drive a car.二、用法1、 表示能力（体力、知识、技能等），此 时可用be able to代替。例如：Mary can speak three languages. 玛丽会说三种语言。= Mary is able to speak three languages.注意：（1）can只有一般现在时和一般过去式
2、；而be able to则有更多的时态。例如：Ill not be able to come this afternoon. 今天下午我将会来。（2）当表示“经过努力才得以做成功某事”时应用be able to，不能用can 。例如：He was able to go to the party yesterday evening in spite of the heavy rain. 尽管很大雨，他昨天能来参加聚会。2、表示请求和允许。例如：-Can I go now? - Yes, you can. / No, you cannot/cant. 此时可与may互换。在疑问句中还可用could
3、, might（不可用于肯定句、否定句或答语）代替，不是过去式，只是语气更委婉。例如：- Could I come to see you tomorrow? - Yes, you can. ( No, Im afraid not. )3、表示可能性猜测。例如：The man over there cant be my uncle. My uncle has gone to Beijing. 那个人不可能是我的叔叔。我的叔叔去北京了。三、练习题( )1-Susans parents have bought a large house with a swimming pool. -It _ be
4、very expensive. Amust Bcan Cmustnt D、cant( )2The notebook_ belong to SarahHer name is on the coverAmight Bcant Cmust Dmustnt( )3.- May I put my bike here?- No，you_You should put it over thereAcouldnt Bneednt Cmustnt Dwont( )4Boys，you_ be sitting in this roomIt is for your teachers onlyAshouldnt Bdon
5、t have to Cwont Dneednt( )5-Whose pizza is this?-I think it_ be mineIm the only one who ordered a pizzaAmust Bcould Cmight Dcant( ) 6. My brother cant sing but he _ play the piano.A. cant B. doesnt C. can D. dont( )7. You look tired. You _ to have a good rest.A. must B. may C. should D. need( ) 8.-
6、Why do you think the man is running ? -He _ be _ for exercise because he is wearing a suit . A. must , running B. cant ; run C. cant ; running D. could ; running ( )9. -Mum , Ive been studying English since 8 oclock. _ I go out and play with Tom for a while?-No, Im afraid not. Besides, its raining outside now. A. Cant B. Wouldnt C. May not D. Wont
