一般过去时：过去某个时间"做了"某事
He visited the museum last Sunday.
标志词：yesterday, last week, in 2020, two days ago
过去进行时：过去某个时刻"正在做"某事
结构：was / were + 动词-ing
I was doing my homework at 8 o'clock last night.（昨晚八点我正在做作业。）
标志词：at that time, at 9 p.m. last night, when..., while...
when 与 while 引导的时间状语（中考高频）
两个过去的动作，一长一短："长动作"用过去进行时，"短动作"用一般过去时：
When the phone rang, I was taking a shower.（电话响时，我正在洗澡。）
While we were having dinner, the lights went out.（我们正吃晚饭时，灯灭了。）
when 后多接短动作（一般过去时）；while 后接长动作（过去进行时）。