一般过去时I did my homework yesterday afternoon.
过去进行时I was doing my homework yesterday afternoon.
过去完成时I had done my homework by yersterday afternoon.
现在完成时I have done my homework.
一般过去时的用法
1）在确定的过去时间里所发生的动作或存在的状态.
时间状语有：yesterday,last week,an hour ago,the other day,in 1982等.
Where did you go just now?
2）表示在过去一段时间内,经常性或习惯性的动作.
When I was a child,I often played football in the street.
Whenever the Browns went during their visit,they were given a warm welcome.
3）句型：
It is time for sb.to do sth "到……时间了" "该……了"
It is time sb.did sth."时间已迟了" "早该……了"
It is time for you to go to bed.你该睡觉了.
It is time you went to bed.你早该睡觉了.
would (had) rather sb.did sth.表示'宁愿某人做某事'
I'd rather you came tomorrow.
4) wish,wonder,think,hope 等用过去时,作试探性的询问、请求、建议等.
I thought you might have some.我以为你想要一些.
比较：
一般过去时表示的动作或状态都已成为过去,现已不复存在.
Christine was an invalid all her life.
(含义：她已不在人间.)
Christine has been an invalid all her life.
(含义：她现在还活着)
Mrs.Darby lived in Kentucky for seven years.
(含义：达比太太已不再住在肯塔基州.)
Mrs.Darby has lived in Kentucky for seven years.
( 含义：现在还住在肯塔基州,有可能指刚离去)
1） 概念：表示过去某时正在进行的状态或动作.
2） 过去进行时的主要用法是描述一件事发生的背景；一个长动作发生的时候,另一个短动作发生.
3) 常用的时间状语
this morning,the whole morning,all day yesterday,from nine to ten last evening,when,while
My brother fell while he was riding his bicycle and hurt himself.
It was raining when they left the station.
When I got to the top of the mountain,the sun was shining.
过去完成时
1） 概念：表示过去的过去
----|-------|-----|---->其构成是had +过去分词构成.
那时以前 那时 现在
2） 用法
a.在told,said,knew,heard,thought等动词后的宾语从句.
She said (that) she had never been to Paris.
b.状语从句
在过去不同时间发生的两个动作中,发生在先,用过去完成时；发生在后,用一般过去时.
When the police arrived,the thieves had run away.
c.表示意向的动词,如hope,wish,expect,think,intend,mean,suppose等,用过去完成时表示"原本…,未能…"
We had hoped that you would come,but you didn't.
3) 过去完成时的时间状语before,by,until ,when,after,once,as soon as.
He said that he had learned some English before.
By the time he was twelve,Edison had began to make a living by himself.
Tom was disappointed that most of the guests had left when he arrived at the party.
现在完成时
现在完成时用来表示之前已发生或完成的动作或状 态,其结果的确和现在有联系.动作或状态发生在过去 但它的影响现在还存在；也可表示持续到现在的动作或 状态.其构成：have (has) +过去分词.
