◆ 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）。