1. 过去将来时的定义
过去将来时主要用于表示过去某个时候看来即将发生的动作或存在的状态。如：
He said he would come here next Friday. 他说他下周星期五来这儿。
I knew that he would help us when we were in trouble. 我知道当我们陷入困境时它会帮助我们。
2. 过去将来时的结构
(1) would + 动词原形。如：
She told us that she would try her best to catch up with other classmates this term. 她告诉我们说她将一切努力在本期赶上其他同学们。
When you asked Li Lei for help, he would never refuse you. 过去当你请她帮忙时，他绝不会拒绝。
(2) was / were going to + 动词原形。如：
He told us that he was going to attend the meeting. 他告诉我说他要参加那次会议。
He said that I was going to be sent to meet her at the railway station. 他说将要拍我去火车站接她
(3) was / were to + 动词原形。如：
The building was to be completed next month. 这座建筑改在下个月竣工。
Li Lei was to arrive soon. 李蕾很快就要到了。
(4) was / were about to + 动词原形。如：
We were about to leave there when it began to rain heavily and suddenly. 就在我们要离开时，天突然下起了大雨。
He was about to have lunch when the bell rang. 就在他要吃中饭的时候，门铃响起来了。
(5) was / were +现在分词。如：
He was leaving the next day. 他第二天要走了。
We were informed that the leaders were coming to our school soon. 我们接到通知说领导们很快要来我们学校。
3. 过去将来时的用法
(1) 过去将来时，一般用于主句为过去时的宾语从句中。如：
He said he would stay with us. 他说他要与我们呆在一起。
He said he would never go there again. 他说他绝不会再去那儿。
(2) 过去将来时，用于虚拟语气中，如：
If I were you, I would not do that. 要是我是你的话，我就不会那样做。
If he were here, he would show us how to do it. 如果他在这儿，他就会向我们展示该如何做了。
4. 拓展
was / were going to + 动词原形；was / were to + 动词原形；was / were about to + 动词原形等结构都可表达当时一种未曾实现的意图或打算。如：
The conference was going to be held the next month. 会议下个月开。
We were to have our class at eight. 八点我们该上课了。
I was about to tell him about it when Wu Dong got in. 就在我要告诉他时，吴东进来了。