过去进行时when和while的用法区别详解：
1.主句过去进行时，从句一般过去时，多用when
主句谓语动词是延续性，从句谓语动词是短暂性
这个搭配通常表示正在做某事的时候被另一件意料之外的事打断

They were having dinner quietly when they heard the cry.
他们正在安静地吃晚饭的时候，（突然）听见了那声大叫。
（他们听见那声大叫的时候，正在吃晚饭）

We were sleeping when she left.
当她离开的时候，我们正在睡觉。

2.主句和从句都用过去进行时，多用while
主句和从句动词都是延续性
They were singing while we were dancing.
我们正在跳舞的时候，他们正在唱歌。
He was working while I was doing my homework.
当我正在做作业的时候他正在工作。


3.when从句中的谓语动词可用短暂性动词或延续性，while从句中的谓语动词必须是延续性。
They were watching TV when she came. （√）
They were watching TV while she came. （×）
[came是短暂性动词，不与while连用]

She came while they were watching TV. （√）
[watch TV是延续性，可与while连用]

若要更深入理解，可点击查看：
when和while的区别

附：初级英语语法基础题
She is very good at painting. She can paint _______ her teacher. 
A. as better as B. as well as C. as good as D. so well as
原文意为“她非常擅长画画。她能够画的和她的老师一样好。”修饰动词paint，用副词，据此排除C；表示原级比较，肯定句中用“as+副词原级+as”，否定句中用“as(so) +副词原句+as”，故选B。

写在最后：区分when和while的关键在于，动词是短暂性还是延续性。希望这篇文章对小伙伴有所帮助。