标志：would + 动词原形
He said he would come here next Friday.
I knew that he would help us when we were in trouble.
The old man would sit on a bench in the quite park for hours without doing anything.
When I worked on that farm, I would get up at 5 am.
If I were you, I would not do that.
If he were here, he would show us how to do it.
1) was / were going to + 动词原形。如：
He told us that he was going to attend the meeting.
She said that I was going to be sent to meet her at the railway station.
2) was / were to + 动词原形。如：
The building was to be completed next month.
Li Lei was to arrive soon.
3) was / were about to + 动词原形。如：
We were about to leave there when it began to rain heavily and suddenly.
He was about to have lunch when the bell rang.
标志：was / were + 动词的现在分词
1. 表示过去某一时刻或一段时间正在进行的动作，过去进行时中常用的时间状语有the whole morning, all day yesterday, from January to March last year等。如：
I was having a talk with Lucy at that time.
They were watching TV at home last night.
2. 表示过去反复出现或习惯性的动作，往往包含说话者赞扬、责备、厌恶等情绪，通常与always, constantly, continually, forever等频度副词连用。如：
My brother was always losing his keys.
3. 表示按计划、安排过去某时刻将要发生的动作，仅适用于部分趋向动词（如go, come, leave, start, arrive等）。如：
He said they were leaving for Beijing this afternoon.
Granny fell asleep when she was reading.
It was raining when they left the station.