as while用法.doc

as的用法小结 as可以作连词、介词及关系代词。现将其用法小结如下: 一、 as作连词的用法: 1. 作当……的时候,引导时间状语从句。注意与when、 while的用法区别。 ① when作当……的时候解,可以指较短的(一点)时间,也可指一段时间。如: When he was at college, he could speak several foreign languages. When the clock struck twelve, all the lights in the street went out. ② while常表示一段较长的时间或一个过程,强调主句谓语动词与从句谓语动词同时发生。如: Work while you work. Play while you play. ③ 但属下列情形时,只用as, 而不用when或while。 A) 用于表示同一个人的两种动作交替进行,指一边……,一边……。如: The girl dances as she sings on the stage. He looked behind from time to time as he went forward. B)表示两个同步发展的动作或行为,译为随着……。如: As time went on / by, she became more and more worried. As children get older, they become more and more interested in the things around them. C)表示两个短促行为或事件几乎同时发生。如: I thought of it just as you opened your mouth. Just as the flying worm hit her face, she gave a loud cry. D) 后接名词表示某一年龄段时,用as。如: As a young man, he was active in sports. 2. as=since, 作既然、由于解,引导原因状语从句,常用来表示已为人们所知或显而易见的原因或理由。如: As / Since youre not feeling well, you may stay at home. As he wasnt ready in time, we went without him. 3. as=in the way that, 作像、按照……的方式解,引导方式状语从句。如: He speaks English as Americans do. Remember, you must do everything as I do. 4. 用于as...as...或not so/ as...as...中,前一个as是副词,后一个as是连词,引导比较状语从句。如: They helped the old man as often as possible. I dont speak English so/ as well as he does. 5. 作虽然、尽管解,引导让步状语从句。常用倒装语序,即adj. /adv. / n.+ as +主语+谓语+主句。如: Tired as they were, they walked on. Child as he is, he knows a lot. (child前不用冠词) 二、 as作关系代词,引导定语从句,作正如、这一点解。如: He is very careful, as his work shows. As is well-known, Taiwan belongs to China. 三、 as作介词的用法: as引导的介词短语大多用作状语,as译为作为;少数情况可引起宾语补足语。如: As a League member, Ill take the lead in everything. (状语) She works as a doctor. (状语) They hav