在通常情况下，时间状语是修饰谓语的，比如你的第一句 I was going to leave yesterday，

本句中的yesterday 是修饰was going to leave 而不是修饰 to leave。即句意为：昨天我打算要离开。而不是：我打算昨天离开。当然，如果是在口语中，可以用重读等方式来改变这种意思，比如要表示后者的意思，可以通过重读 leave 和 yesterday 来表示。

老师们好，这些句子会引起不同意思吗?

1. I was going to leave yesterday. 

我昨天只是打算走，还是说打算昨天走？

回答如下：

过去将来时态一般直接与表示过去的时间状语连用，一般在宾语从句使用，因此改为

I said that I was going to leave.

2. I was leaving yesterday.

这句会不会有歧义呢？把 yesterday  提至句子前会不会说 昨天，我要走，但是什么时候走不知道？

改为：I left yesterday

3. I would leave yesterday.

这个有无歧义？Yesterday, I would leave. 会不会是说我将要走，什么时候走不知道？

4. I was about/due to leave yesterday.

这个会不会有歧义？那此外能不能说 I'm going to do my homework now. 意思为我现在正打算做作业，什么时候还没决定呢？

(备注:带有一般过去时的时间状语，句子一般只能用一般过去时态）

He was a student five years ago.

He planted an apple tree in 2014.

Tom joined the army in 2008.

I met Tom's mother in the street yesterday.

Mary visited his grandparents the day before yesterday.

A car accident happened here last night.

(过去将来时态一般与其主句为一般过去时的宾语从句连用）

She said that she would pay a visit to Beijing.

She said that shewas going to visit Beijing

(1)过去将来时的含义
过去将来时表示在过去某个时间看来将要发生的动作或存在的状态。过去将来时常用于宾语从句和间接引语中：
I didn’t know if he would come.
我不知道他是否会来。
They never knew that population would become a big problem.
他们从来都不知道人口问题将会成为一个大问题。
She didn’t tell me where she would go.
她没有告诉我她要去哪儿。
Betty said she would visit the Great Wall next Saturday.
贝蒂说下周六她要去参观长城。
(2)过去将来时的表达法
A:“would+动词原形”。常表示按计划或安排即将发生的事。
He said he would come to see me.
他说他要来看我。
He told me he would go to Beijing.
他告诉我他将去北京。
B:“was/ were+going to+动词原形”。常可用来表示按计划或安排即将发生的事。
She said she was going to start off at once.
她说她将立即出发。
I was told that he was going to return home.
有人告诉我他准备回家。
此结构还可表示根据当时情况判断有可能但不一定会发生某事。
It seemed as if it was going to rain.
看来好像要下雨。
(3)come， go， leave， arrive， start等动词可用过去进行时代替过去将来时。
He said the train was leaving at six the next morning.
他说火车将于第二天早晨六点离开。
She told me she was coming to see me.
她告诉我她要来看我。
(4)条件状语从句和时间状语从句中须用一般过去时代替过去将来时。
I didn’t know when she would come， but when she came I would let you know.
我不知道她什么时候来，但她来了我会告诉你。
The teacher said that it would be very difficult to make progress if I didn’t work hard.
老师说，如果我不努力学习的话，就很难取得进步。