过去进行时讲义（定义，结构，时间状语，用法）

接下来贝贝英语分享的是过去进行时的讲义，先看下面3个例子。
1. What were you doing at six yesterday? I was drawing. 
2. When I was doing the housework., my husband phoned me from the office. 
3. He cut himself, while he was shaving. 
一、定义：表示过去某一时刻/过去的一段时间里正在进行的状态或动作。
    I was watching TV when she came to see me.
Mum was doing some washing yesterday evening.
否：Mum was not (wasn’t) doing some washing yesterday evening.
疑：Was mum doing some washing yesterday evening?
二、结构
肯：主语 + was (were) + 现在分词… 
    否：主语 + wasn’t / weren’t + 现在分词…
    疑：was (were) + 主语 + 现在分词…?
    答：Yes, 主语 + was / were.    No, 主语 + wasn’t (weren’t)
    was, were根据主语决定。
三、标志性时间状语：
    过去某时刻：at this time yesterday, at that time,then, at 9 last night.
过去一段时间from…to last night,those days
四、用法：1.过去某时刻What were you doing at six yesterday? I was drawing. (常用于单句中) 即at+过去时间点
2. 表过去某段时间内一直持续的动作，常和those days等连用。
   He was writing a novel those days.
3. 一般过去时和过去进行时常出现在一个句子里。(复合句中)
       The students were doing exercises when the teacher came in. 
延续时间较短的用一般过去时,延续时间较长的用过去进行时。
注意：从句是一般过去时只能用when，不用while.
4. 表主句和从句同时进行的过去的动作，常用连词 while.
       My granny was cooking while I was washing my face yesterday. 
总结：一般过去时强调过去某个时间发生的动作或存在的状态，过去进行时强调过去某个时间正在进行的动作。