2动词与句型.doc

No. 2 动词与句型 一．动词： 动词主要分为四类：连系动词，行为动词，助动词和情态动词。 情态动词没有人称与数的分别，可以直接加NOT变否定，也可以直接提前变疑问，后面还直接加动词原形，可以说是万能动词。 1． can: 1) 能，能够 = be able to I can swim. She can drive a car. They can speak English. 2）可能= May Can he come again on Sunday? I will come back as soon as I can. 3）允许= May. could更为客气。 Can I use your pen? 4）Can与BE一起用于否定及疑问句表示怀疑，不相信： Can he be a liar? He can’t be a liar. 5) can’t but只得，只能, can’t help V-ing忍不住，不禁, cannot …too…无论怎样…也不过分；要尽量…; I can not but let him go. I can’t help laughing on hearing such a funny story. You cannot be too careful in crossing the street. You cannot begin the practice too early. 练习开始得越早越好。 You cannot be too quiet in having a class.上课时要尽量安静。 2．May: 1). 表示请求, 但回答时，只能用can’t, mustn’t表示否定回答。 May I use your pen? Yes, you may. No, you can’t. 或: No, you mustn’t. 2). 表示可能： He may come back on Sunday. 3). May与Be一起，表示把握不大的猜测： He may be at home now. 4). may as well = might as well: 不妨，还是…为好。 Shall we walk or take a bus? We may as well walk. We might (just) as well walk. 5). may well = have good reasons是有理由的。 You may well refuse him. 6). 表示祝愿： May you succeed. May you have a great holiday. 3. Must: 1). 表示“必须”， 常为主观看法。而have to为客观要求。 You must study hard. I have to study hard because I will take an exam next week. 2). mustn’t表示“禁止，不允许”： You mustn’t talk while the teacher is giving a lecture. 3) 对于以must提问的一般疑问句，否定应用needn’t代替。 Must I do it now? Yes, you must. No, you needn’t. 4).Must与be一起在肯定句中表示把握极大的可能： He must be at home now because he is sick in bed. 4. Should与ought to:（义务，劝告，责任）应该 You should study hard in order to get high marks in the finals. You ought not to play with him, because he is a very dirty boy. Ought we do it right now? 5. would rather宁肯，宁愿 I would rather buy a new one. I would rather walk there than wait here. 6. had better最好 You’d better leave the dog alone. We’d better tell her the truth. 7. 情态动词与完成式： 1). Can have V-ed2表示对过去行为的怀疑或不肯定： Can he have finished the exercises? He can’t have made such a mistake. 2)．might