英语四级情态动词用法 情态动词属于非实意动词，它虽具有一定的词义，但这种词义并不完整，语法上也不能单独构成谓语，它必须和另一个实意动词一起构成谓语才能表达完整的意思。情态动词是一类非常活跃的非实意动词，归纳起来，情态动词在句子中主要有三种用法： 1.情态动词的非推测性用法 其用法是用来表示能力、许可、必要、义务、命令、劝告、询问、需要、应该、敢于等概念或态度，这类情态动词有：can(could)，may(might)，shall(should)，will(would)，must， oughtto，need，dare 等，例如： Children，you can eat something you like. Everybody must pay the fare，but you need not do so right away. How dare you come out without your parents’permission? I would rather stay at home than go with you. Ought not parents to give their child more care? You are not so young;you should not do such silly things any more. 疑问句中的情态动词和答语中的情态动词有固定的搭配形式。例如： Could I borrow your bike for a while? Yes，you can.(Yes，please.) No，you can not. May I discuss something on practicing spoken English with you now? Yes，you may.(Yes，of course.) No，you mustn’t. Need everyone fill in this application form immediately? Yes，everyone must.(Yes，everyone do.) No，they needn’t. Must we hand out emergency rations to these famine refugees this instant? Yes，you must. No，you they needn’t. No，you don’t have to. 2.情态动词的推测性用法 人们常常会对客观事物做出自己的推断，当情态动词用来表示说话人对事物的推测、推断时，就具有情态动词的推测性用法。可以用作推测的情态动词有can，could，may，might，must，ought to， should，will和 would。它们做出可能性的推测、推断、预料的程度是不同的，might 最弱、最没有把握，而 must 最强、把握最大。例如： It’s nine o’clock.My friend couldn’t come to see me. This boy must fail in exam from his sad face. It’s five past eight.There ought to be many students waiting for the door opening. She should be a c...
