when和while引导的时间状语从句
when和while引导的时间状语从句主要有以下区别：
1. when可以和延续性动词连用，也可以和短暂性动词连用；而while只能和延续性动词连用。例如，when you think you know nothing, then you begin to know something（当你以为自己一无所知的时候，你就是在开始知道一些事物了）；Strike while the iron is hot（趁热打铁）。
2. when从句的谓语动词可以在主句谓语动作之前、之后或同时发生；while从句的谓语动作必须是和主句谓语动作同时发生。例如，when he had finished his homework, he took a short rest（当他完成作业后，他休息了一会儿）；While my wife was reading the newspaper, I was watching TV（当我的妻子在看报纸时，我在看电视）。
3. when有时表示“就在那时”，例如：We were about to leave when he came in.（我们就要离开，就在那时他进来了）。
4. while有时还可以表示对比，例如：I like playing football while you like playing basketball（我喜欢踢足球，而你喜欢打篮球）。
