英语的过去进行时

过去进行时,是表示过去某时正在进行的状态或动作.
用法：
一、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.常用的时间状语this morning,the whole morning,all day yesterday,from nine to ten last evening,when,while例如：
We were watching TV from seven to nine last night.昨天晚上七点到九点的时候我们在看电视What was he researching all day last Sunday?上周日他一整天都在研究什么?
My brother fell while he was riding his bicycle and hurt himself.我哥哥骑自行车的时候从车上摔下来,受伤了.
It was raining when they left the station.他们离开车站的时候天正在下雨.
When I got to the top of the mountain,the sun was shining.当我到达山顶的时候,阳光灿烂.
二、 过去进行时可以表示在过去某个时间点发生的事情.时间点可以用介词短语、副词或从句来表示.如：What was she doing at nine o'clock yesterday?昨天晚上九点她在做什么?(介词短语表示时间点)
When I saw him he was decorating his room.
当我看见他的时候他正在装饰房间.(when从句表示时间点)
三、 在复合句中,如果主要动作和背景动作都是延续的或同时发生的,那么主从句的动词都可用过去进行时.例如：While he was waiting for the bus,he was reading a newspaper.他边等车边看报.(两个动作都是延续的)
He was cleaning his car while I was cooking.他擦车时我在做饭.(两个动作同时进行)
四、 通常不能用于过去进行时的动词主要有：agree,be,believe,belong,care,forget,hate,have(拥有),hear,know,like,love,mean,mind,notice,own,remember,seem,suppose,understand,want,wish等.例如：
误：I was knowing the answer.
正：I knew the answer.我知道答案.
误：I wasn't understanding him.
正：I didn't understand him.我不明白他的意思.