一.引导时间状语从句时,WHILE连接的是时间段,而WHEN连接的多是时间点
例如What does your father do while your mother is cooking?
What does your mother do when you come back?
二,WHILE可以连接两个并列的句子,而WHEN不可以
例如I was trying my best to finish my work while my sister was whtching TV
三,WHEN是特殊疑问词,对时间进行提问,WHILE不是.
例如,When were you bron?
1）as,when 引导短暂性动作的动词.
Just as / Just when / When I stopped my car,a man came up to me.
2）当从句的动作发生于主句动作之前,只能用when 引导这个从句,不可用as 或 while.
When you have finished your work,you may have a rest.
3）从句表示"随时间推移"连词能用as,不用when 或while.
As the day went on,the weather got worse.
日子一天天过去,天气越变越坏.
