完型填空中总是出现的as,when,since,beore,while怎么区分?

Question

不要复制别的答案,给点实际的...

Answer 1

1.首先从词义上分：as表示“当......时候”，when“当......时候”,since表示“自从”，while“当......时候”， before表示“在......之前”根据这一项，可以区分开since和before与其它三项。
2.从细微差别来看，as表示一边一边，when表示这时， while表示对比。
He was doing his homework while she was watching TV.他在做作业的时候，她在看电视。
He was doing his homework as he was listening to music.他边做作业边听音乐。
He was doing his homework when a cat came into his room.他一直在做作业这时有一只猫进入的他的房间。