如果表示过去发生的动作,while 引导的时间状语从句和主句可以都用过去进行时或者一般过去时,意思上没有什么区别。when 不能用于这种情况。例如:
I cooked the dinner while he played the piano. = I was cooking the dinner while he was playing the piano. 他在弹钢琴,我在做饭。(摘自《薄冰英语惯用法词典》p.1317)
While you were reading the paper, I was working. 你看报的时候,我在干活儿。(摘自《牛津英语用法指南》第四版252.2节)
Jack cooked supper while I watched TV. 我看电视的时候,杰克在做晚饭。(同上)