(一)助动词有be, have, do, will, shall。它们本身没有词义,只和实义动词的一定形式构成复合谓语,用来表示时态和语态,构成否定、疑问及加强语气等。
1、be (am, is, are, were, been)
(l)be + -ing构成进行时态;(2)be + 过去分词构成被动语态;(3)be + 动词不定式构成复合谓语:①表示按计划安排要发生的事。The prime minister is to visit Japan next year. 总理将于明年访问日本。② 用于命令。Youre to do your homework before you watch TV.你得做完了作业才能看电视。
2、have (has, had)
(1)have+过去分词构成完成时态。如:Have you seen the film ? (2)have been + -ing构成完成进行时态。如:What have you been doing these days? 这些日子你一直在干什么?
3、do (does, did)
(1)do not + 动词原形构成行为动词的否定式。如:His brother doesnt like playing basket.;(2)Do + 主语 + 动词原形构成行为动词的一般疑问句。Does he go to school by bike every day? (3)do + 动词原形用于祈使句或陈述句中表示加强语气。如:I did go to see him, but he wasnt in我确实去看望他了,但他不在家。Do do some work. 请一定做点什么;(4)代替前面刚出现的动词以避免重复。My mother told me to go to bed early. So I did.
4.will, shall (would, should)
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