情态动词的用法大全(2)

　　1. he play isn’t interesting, I really must go now.

　　2. I had to work when I was your age.

　　3) 表示推测、可能性(只用于肯定的陈述句)

　　1. You’re Tom’s good friend, so you must know what he likes best.

　　2. Your mother must be waiting for you now.

　　四、 dare, need

　　1) dare作情态动词用时, 常用于疑问句、否定句和条件从句中, 过去式形式为dared。

　　1. How dare you say I’m unfair?

　　2. He daren’t speak English before such a crowd, dare he?

　　3. If we dared not go there that day， we couldn’t get the beautiful flowers.

　　2) need 作情态动词用时, 常用于疑问句、否定句。在肯定句中一般用must, have to, ought to, should代替。

　　1.You needn’t come so early.

　　2. ---- Need I finish the work today?

　　---- Yes, you must. / No, you needn’t.

　　3) dare和 need作实义动词用时， 有人称、时态和数的变化。在肯定句中，dare后面常接带to的不定式。在疑问句和否定句中，dare后面可接带to或不带to的不定式。而need后面只能接带to的不定式。

　　1. I dare to swim across this river.

　　2. He doesn’t dare (to) answer.

　　3. He needs to finish his homework today.

　　五、 shall, should

　　1) shall 用于第一人称，征求对方的意见。

　　What shall we do this evening?

　　2) shall 用于第二、三人称，表示说话人给对方的命令、警告、允诺或威胁。

　　1. You shall fail if you don’t work hard.(警告)

　　2. He shall have the book when I finish it.(允诺)

　　3. He shall be punished.(威胁)

　　六、 will, would

　　1) 表示请求、建议等，would更委婉。

　　Will / Would you pass me the ball, please?

　　2) 表示意志、愿望和决心。

　　1. I wi