当表示"当"这个时间状语的时候,while可以说是when的一种特殊形式,意思就是,该用while的时候用when也不会错.

while主要用在两个进行时动词的中间,而when的话就没有那么多要求,when的两端无论什么形式动词都无所谓

WHILE:my father was reading while I was watching TV.

WHEN: My father was reading when I was watching TV/when I came in

My father go out when I came in

另外:while不表示"当"的时候,可以表示对比.

sample: I am a student while my brother is a worker.