和一般将来时一样，只不过把助动词be变为过去式，把will，shall变为过去式。

I didn't know if he would come.

=I didn't know if he was going to come.

我不知道他是否会来。

She was sixty-six. In three years，she would be sixty-nine.

她66岁了。三年后，她是69岁。

She told us that she would not go with us，if it rained.

她告诉我们，如果下雨，她就不和我们一起去了。

I didn't know how to do it. What would be their ideas?

我不知如何去做，他们会有什么想法呢?

2.过去将来时常可用来表示过去习惯性的动作。此时，不管什么人称，一律用would。

This door wouldn't open.

这扇门老是打不开。

Whenever he had time，he would do some reading.

他一有时间，总是看书。

I would play with him when was a child.

当我还是孩童时，总是和他一起玩。