过去现在时用来描述过去想的、说的、感觉到的、保证的、计划的，将来做的事情。
Like simple future, future in the past has two different forms in English: would and was going to. Although the two forms can sometimes be used interchangeably, they often express two different meanings.
像一般将来时一样，过去将来时在英语中有两种不同的形式： would 和 was going to 。 虽然这两种形式有时可以互换使用，但它们往往表达两种不同的含义。
格式（FORM） Would
[ would + 动词（VERB）]
例句 Examples:
I knew you would help him.
I knew you would not help him.
格式（FORM） Was / Were Going To
[ was / were + going to + 动词（VERB）]
例句 Examples:
I knew you were going to go to the party.
I knew you were not going to go to the party.
“ Would ”用于志愿或承诺，“ was going to ”用于计划。
此外，这两种形式都可以用来预测未来。
例句 Examples:
计划 plan
I told you he was going to come to the party.
Jane said Sam was going to bring his sister with him, but he came alone.
自愿行动 voluntary action
I knew Julie would make dinner.
预言 prediction
I had a feeling that the vacation was going to be a disaster.
承诺 promise
He promised he would send a postcard from Egypt.
记住没有未来的时间条件（REMEMBER No Future in Time Clauses）
Like all future forms, future in the past cannot be used in clauses beginning with time expressions such as: when, while, before, after, by the time, as soon as, if, unless, etc. Instead of using future in the past, you must use simple past.
像所有将来时形式一样，过去将来时（ Future in past ）不能用于以时间表达式开头的从句中，例如：when, while, before, after, by the time, as soon as, if, unless 等。你必须使用一般过去时，而不是使用过去将来时（ Future in past ）。
Examples:
不正确 I already told Mark that when he would arrive, we would go out for dinner.
正确的 I already told Mark that when he arrived, we would go out for dinner.
主动（Active）和被动（Passive）
Examples:
主动（Active） I knew John would finish the work by 5:00 PM.
被动（Passive） I knew the work would be finished by 5:00 PM.
主动（Active） I thought Sally was going to make a beautiful dinner.
被动（Passive） I thought a beautiful dinner was going to be made by Sally.
