（）you are doing that,I’ll go and get some water

while只指"时间段",不指"时间点",从句的动词只限于持续性动词。如：While I slept,a thief broke in。在我睡觉时,盗贼闯了进来。as soon as 引导时间状语从句,表示“一……就……”。如果主句用将来时或情态动词或祈使句,从句必须用一般现在时代替将来时。如：I’ll tell him the news as soon as he comes。他一来我就告诉他那消息。She may come as soon as she finishes the work。事情一做完她就可以来。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。并且when有时表示“就在那时”。例如：When she came in,I stopped eating。她进来时,我在吃饭。(瞬时动词)When I lived in the countryside,I used to carry some water for him。当的住在农村时,我常常为他担水。（延续性的动词）We were about to leave when he came in。我们就要离开,就在那时他进来了。While引导的从句的谓语动作必须是延续性的,并强调主句和从句的动作同时发生（或者相对应）。并且while有时还可以表示对比。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。我喜欢踢足球,而你喜欢打篮球。（对比）