while主句和从句的时态

　　1、当while表示同时的时候，主句和从句的时态一致，既可以都用一般现在时，又可以都用一般过去时。表示过去同时发生或现在正在同时发生的事。比如：Father was cooking the meal while i was doing my homework。2、在while所引导的状语从句中，如果从句的主语和主句的主语相同，且动词又是be动词时，从句的主语和be动词往往可以省略。

　　while的具体用法：

　　1、“当……时候”，引导时间状语从句，从句动作必须是延续性的。

　　Please don't talk so loud while others are working。

　　While I was cleaning the window，my finger was seriously cut。

　　2、“虽然，尽管”相当于although，引导让步状语从句，常把while放在句首。

　　While she is a top student，she has some shortcomings。While the Internet is bridging the distance between people，it may also be breaking some home or will cause other family problems。

　　3、“只要，如果”等于as long as，引导条件状语从句。

　　There is hope while there is life。