一般过去时
1.基本用法
（1）常用来表示过去某一时间所发生的动作。
（2）表示在过去一段时间内经常发生的动作或存在的状态。
2.基本结构
(1)主+be动词(was/were)+名（代/介词短语）
（2）主+动词的过去式+宾
(3)动词的过去时变化（略）和含过去时句子的肯定、否定、疑问变化。
did, didn’t, Did...?
e.g.Where were you at that time?
I was sorry to hear that.
Who left the door open?
What did you major in?
Did you go home yesterday? Yes, I did. No, I didn’t.
I didn’t go home yesterday.
3.过去时的句子常带有标志性的时间状语
...yesterday, at that time
...ago, last year, week, just now etc.
4.Ago
(1)多用于过去时。
（2）它所指时间是从现在算起。
It was 20 years ago when Jack was a boy of fifteen.
5.Before
(1)多用于过去完成时
（2）它所指时间是从过去某一时刻算起（可与previously换用）。
Last summer, I finally left the firm that I had joined 18 years before.
责编：Lisa
