时态详解：过去将来完成进行时
一、过去将来完成进行时的用法
过去将来完成进行时表动作从过去某一时间开始一直延续到过去将来某一时间。

动作是否继续下去，由上下文决定。

如：
I heard by July you’d have been teaching here for ten years.我听说到七月份，你就在这里教了10年书了。

二、过去将来完成进行时的构成
过去完成进行时由“would have been+现在分词”构成。

如：
He said that by the end of the spring term he would have been studying English for three years. 他说到了春季学期末，他就学了三年英语了。

I knew by that time he would have been working there for 30 years. 我知道到那时他他就在那儿工作满30年了。

S he told me she’d have been teaching in that university for 20 years by that summer.她告诉我到年年夏天她在那所大学教书就满20年了。

三、间接引语与过去将来完成进行时
在间接引语中，若主句为过去时态，则用于宾语从句中的间接引语则要把将来完成进行时改为过去将来完成进行时。

如：
I know by this time next week y ou’ll have been working here for 30 years.
→I knew by that time he would have been working there for 30 years.
She will have been teaching in this university for 20 years by this summer.
→She told me she’d have been teaching in that university for 20 years by that summer.
五、过去将来完成进行时的情态意义
“would have been+现在分词”结构除用于表示过去将来完成进行时外，有时其中的 would 也可能是情态动词，具有情态意义，比较表示推测或猜想等。

如：
“What interesting job have you found?” Helen asked him; he knew she would have been thinking about it. “你找到什么有趣的工作啦?”海伦向他问道。

他知道海伦一定会一直想这件事的。