呃、给你While的详细用法吧.
While 连词：
1.引导两者对比的句子、表然而的意思.例：I like reading books , while he likes playing games with kids .
2.引导时间状语时、表当什么时、一般主句和从句的谓语都用做进行时.同时,While引导的句子的谓语要是延续性动词.而when所引导的句子的谓语可以是延续性的动词也可以是非延续性动词.这是它们两者的最大区别处.
例：My mum was washing clothses , while my dad was watching TV .
When I reached there , he has left .
When I came here , he was writting a letter .
while 名词 一会儿的意思. after a while