一、构成：
1） 肯定形式：S+动词过去式（v.+ed）+O.
2） 否定形式：S+助动词did not+动词原形+O.
3） 疑问形式：助动词Did +S.+动词原形+O.
eg. Last week Tom helped his parents do housework at home
二、用法：
1）表示过去某时间发生的动作或存在的状态。
I got up at six this morning.
We visited the factory last week.
2) 表示过去的习惯或经常发生的动作。
When I was in the countryside, I often swam in the river.
3) 和一般过去式连用的时间状语
Last night, yesterday, last week, some years ago, in 1995, in the past , the other day, at that time, just now 等。
三、形式 构成 例词
过去式与过去分词
(规则变化) 直接加-ed work-worked
以e结尾的动词，直接加-d live-lived
以辅音字母加y结尾的动词，
变y为i加-ed carry-carried, study-studied
以重读闭音节结尾且末尾只有一个辅音字母的，双写加－ed stop-stopped, plan-planned
eg. --- How much money did you ____ on the dictionary?
--- Seventy-nine yuan.
A. pay B. spend C. cost D. take 答案 (B)
The doctor ____ a ____ boy yesterday.
A. had saved; dying B. saved; dead C. has saved; dead D. saved; dying 答案 (D)