when,while+,as.doc

when, while和as的区别when引导的从句的谓语动词可以是延续性的动词，又可以是瞬时动词。when有时表示“就在那时”，whenand then; at that moment (正在那个时候)； 还可以表示从句动词的动作在主句动词的动作之前 或之后发生。有很多情况已经约定俗成，可以当成句型来记忆。例如： be going to do . when .did .be about to do. when. didi.be on the point of doing. when .did.be starting to do. when . did.be doing. when . did.had just done.when. did.had hardly done.when.did.had scarcely done.when.did.had no sooner done. when. did.When she came in, I stopped eating. (瞬时动词) When I lived in the countryside, I used to carry some water for him.（延续性的动词） We were about to leave when he came in. When I had read the article, he called me. ( 从句动作发生在主句之前，注意时态表达，只能用when )When I got to the cinema, the film had begun. (从句的动作发生在主句之后，只能用when,并要注意时态)He was about to leave, when the telephone rang. ( 此时不能放在句首。主句动词一般表达 “正在” “即将”.at the moment/and then)许多同学只知道 when 表示“当的时候”，其实还可以是“尽管”、“虽然”、“既然”、“本该.却.（对比）、“如果”、“考虑到”的意思。又虽然He walks when he might take a taxi. 尽管他可以坐出租车，但他却走路。He stopped trying when he might have succeeded next time. 尽管他本来下次就可以成功的了，但他却停止努力了。The boy was restless when he should have listened to the teacher carefully. 这男孩子本来应该专心听老师讲的，但他却坐立不安。这男孩子本来应该专心听老师讲的，但他却坐立不安。如Come when you are ready. （if）I cant tell you anything when you wont listen.（although)She stopped trying, when she might succeed next time.(although)They have only three copies when we need five. (本该.却.)When the wind blows, all the doors rattle.(whenever)(D)：Why do you want a new job _ youve got such a good one already?A. that B. where C. which D. whenHe was about to tell me the secret _ someone patted him on the shoulder.A. as B. until C. when D. while 分析：答案 C。最大干扰项是A。when 意为“这时(突然)”，主要用于某一动作突然发生于另一动作正在进行或刚要发生之时。此时的 when 可以连用副词 suddenly，也可以不连用它，但值得注意的是，同学们不能单独用 suddenly 来代替 when，如下面各题的答案选A，不选B：I was about to go out _ the telephone rang. A. when B. suddenly C. as soon as D. directly We were swimming in the lake _ the storm started. A. when B. suddenly C. until D. beforeShe was walking down the road _ she heard someone shouting for help.A. when B. suddenly C. until D. before While引导的从句的谓语动作必须是延续性的，用于时间较长时；并强调主句和从句的动作同时发生（或者相对比 译为而）。例如： While my wife was reading the newspaper, I was watching TV. (was reading是延续性的动词，was reading和was watching同时发生) I like playing football while you like playing basketball.（对比）Would buy me some stamps while you are in the post office? While locked up in prison, she wrote her first novel.While Mary was writing a letter, the children were playing outside.As表示“一边一边”，as引导的动作是延续性的动作？不能是状态动词，一般用于强调主句和从句动作同时发生；as也可以强调“一先一后”、表示对比时，用于发生时间较短时例如：We always sing as we walk.（as表示“一边一边”） As we was going out, it began to snow.（as强调句中两个动作紧接着先后发生，而不强调开始下雪的特定时间） 有时这三个连词可以互换，有时不可以。It was raining hard when (as) I got there.( 动作同时发生，when可换为as, 但不能换为while，因为get是点动词.)Mother was worried because little Alice was ill, especially as (when/ while) father was away. (此时as ,when, while可通用) while, as不能代替 While the alien was buying a souvenir, the girl