一、过去进行时1.定义
过去进行时表示过去某一时刻正在进行的动作或过去某一阶段一直在进行的动作。
eg: I was reading in the library at that time.
那时我正在图书馆看书。

2.构成
过去进行时由“was/were＋现在分词”构成。【注意】am,is的过去式是was;are的过去式是were。

3.句式变换
一般疑问句及回答: Was/Were＋主语+v. ing形式＋其他?肯定回答:Yes，主语+was/were.
否定回答:No，主语+wasn't/weren't.
eg:—Were you watching TV at home at 9 o'clock
yesterday evening?昨天晚上9点你在家看电视吗?—Yes,l was./ No, 1 wasn't.是,我是。/不,我不是。