过去进行时

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过去进行时的形式
过去进行时由was(第一、三人称单数)或were (其余各人称和数)加现在分词所构成。
过去进行时的基本用法
表示在过去某一时刻或某一段时间正在进行的动作，这一特定的时间往往须用时间状语来表示。如：
She was reading an English magazine when I came in.我进来时她在看一本英文杂志。
It was getting dark.天黑了。
They were working all day yesterday.他们昨天整天工作。
We were cleaning the auditorium from 7 to 9 last night.昨晚七点到九点我们在打扫大礼堂。
I met him when he was crossing the street.他过街时我碰见他。 过去进行时的其他用法
1)表示移动的动词go，come，start，stay，leave等的过去进行时，可以表示过去将来发生的动作。如：
They wanted to know when we were leaving for Shanghai. 他们想知道我们什么时候到上海去。
She asked whether he was starting then ext day.她问他是否第二天就动身。

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2)动词go的过去进行时态加动词不定式，可以表示在过去某一时间之后将要发生的动作。如：
They said they were going to set up a nursery.他们说他们要设立一个托儿所。
She said the foreign guests were going to visit the Shanghai in dustrial Exhibition.她说外宾要去参观上海工业展览会。
The monitor announced that our new teacher was going to speak to us.班长宣布新老师要跟我们讲话。
3)过去进行时可用来描写故事发生的背景。如： It was a dark night. The wind was blowing hard and the rain was falling heavily. A young woman suddenly appeared on the riverbank. it was Xier. She had just escaped from Huang Shiren's house.那是一个漆黑的夜晚。风刮得很厉害，雨下得很大。一个年轻妇女突然出现在河岸上。这就是喜儿。她刚从黄世仁的家里逃了出来。

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过去一般时与过去进行时用法比较
过去一般时通常表示过去发生的一个单纯的事实，而过去进行时则表示在过去某一时刻或某段时间正在进行的动作，强调在这一过程中所进行的动作或展开的情景。试比较：
We built a bridge last winter.去冬我们修了一座桥。(意即去冬我们做了这件事，桥已经修好了。)
We were building a hydro-electric station last winter.去冬我们在修水电站。(意即去冬我们一直在修水电站，修完与否不详)
I wrote a letter home last night. 昨晚我写了一封家信。(意即)昨晚我做了这件事，信写完了。)
I was writing a letter to my pen friend in America last night. 昨晚我在给我的美国笔友写信。(意即昨晚我一直在写信，不一定写完)