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 researching1 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 reading2 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 understanding3 him.
正：I didn't understand him. 我不明白他的意思。
典型例题：
1) Mary ___ a dress when she cut her finger.
A. made B. is making C. was making D. makes
答案C. 割伤手指是已发生的事情，应用过去时。同时，when表时间的同时性，“玛丽在做衣服时”提供事情发生的背景，因此用过去进行时。
2) As she ___ the newspaper, Granny ___ asleep.
A. read; was falling B. was reading; fell C. was reading; was falling D. read;fell
答案B.句中的as = when, while，意为"当……之时"。描述一件事发生的背景时，用过去进行；一个长动作发生的时候，另一个短动作发生。句意为 "在她看报纸时，奶奶睡着了。"句中的 fell (fall的过去时)，是系动词，后跟形容词，如：fall sick。
过去进行时和一般过去时的区别
一．一般过去时叙述旧事，过去进行时描述背景。
Ａ、一般过去时
１）叙述过去状态、动作或事件
He went to Beijing the other day.（带具体时间）
２）表示过去的习惯
a) would ,used4 to与过去时
would 表间断性不规则的习惯，常带频率时间
used to 表一贯性有规律的习惯
They used to meet and would sometimes exchange one or two words.
He smoked a lot two years ago. （过去行为）
b) Would 用于文中不用于句首，只表过去习惯。
Used to 表今昔对比的含义，叙述习惯动作可与would 换用。
When he was a boy , he would often go there . （叙述过去）
She isn't what she used to be. (今昔对比)
c) 表示状态时一般只用used to
Tom used to be fat /There used to stand a tree there. (状态)
d) was (were) used to +ving表示“合适于，适应于…..”
He used to work at night . (“习惯”表经常)
He was used to working at night. (习惯表适应)
３）表示过去的经历，平行动作，依此事件用一般过去时。
He sat there and listened to the radio.(依此发生)
４）表示客气委婉的语气，用于情态动词，助动词和want , wonder , hope 等
How did you like the film? / Could you help me?
B. 过去进行时
－表示在过去某阶段或某一时刻正在发生
What were you doing at 8:30 last night? (过去某时刻正在发生)
－短暂性动词用过去进行时表示按计划、打算
During that time he was going with us.(表示打算)
－与always ,often ,usually 等连用表喜爱，讨厌等感情色彩。
He was always Changing his mind.
二、过去进行时与一般过去时的区别
A. 进行时表某一行为的“片断”一般时表示行为的“整体”和存在的状态。
I was reading the book at that time. (未读完，“读”的片段)
I read the book yesterday. (已读完，表整个“读”)
B、一般持续时间状语多与进行时连用
It was raining all night.(优先用was raining ,rained 为持续动词，故也可使用)
He was writing a letter the whole of afternoon. (短暂动词与持续时间连用，表反复，连续发生，不可用一般过去时)
C、while 时间状语从句中用短暂动词时只能用进行时。
例：He broke a chair while he was jumping up and down.
D、While 所在主从句动作大致持续相等时主从句一般都用进行时，但若是持续动词可都用一般过去时，两个动作一长一短时短的用一般时，长的用进行时。
I was cooking the dinner while he was playing the piano.(平行)
I cooked the dinner while he played the piano.
I saw him while I was walking to the station.
三、英语中有四类动词一般不用进行时（不用现在进行时和过去进行时）
1)表心理状态、情感的动词，如love ,hate ,like ,care ,respect5 ,please ,prefer ,know 等，若用进行时则词意改变。
I’m forgetting it . (=beginning to forget )
2)表存在、状态的动词，如appear ,exist6 ,lie ,remain ,stand ,seem等
3)表感觉的动词，如see ,hear ,feel ,smell ,sound ,taste等.
4)表一时性的动词，如accept ,allow ,admit7 ,decide ,end ,refuse ,permit8 ,promise等。
四、例题
考题1 As she ____the newspaper ,Granny ____ asleep .(95)
A. read /was falling B .was reading /fell
C. Was reading /was falling D. read/fell
分析 时间从句的动作长，而“入睡”动作短，故前者用过去进行时，而较短动词用一般过去时，选B
考题2 Tom ___ into the house when no one ___ .
A. slipped9/was looking B. Had slipped /looked
C. slipped/had looked D. was slipping /looked
分析 此题先要理解好when ，表“此时”，说明主句中slipped是较短行为，而look是较长行为的片断，即汤姆溜进房子，此时没人瞧见，故选A为正确
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