1、when引导的从句的谓语动词即可以是延续性动词，又可以是瞬间动词，可用于主句从从句动作同时发生或从句先于主句动作发生的情况
2、when有时可用作并列连词，引导并列句，意为“正在这时”相当于and at that time，常用于be doing sth. / be about to do sth./ be on the point of doing sth.
3、while引导的从句的谓语动词必须是延续性的，强调主句和从句的动作同时发生，如please don't talk so loud while others are working
4、while有时可用作并列连词，意为而，却，表示对比，例如I like playing football while you like playing basketball
5、在as long as和so long as引导的时间状语从句中这两个连词表达长达...之久。例如you can keep the book as long as you like
6、each time, every time和whenever也可引导时间状语从句，例如，you grow younger every time I see you.
