什么是过去将来完成时？
过去将来完成时是英语中的一种复合时态，用来描述在过去某个时间点之前将会完成的动作或事件。它表示过去的某一时刻之前已经完成的将来动作。以下是一些例子，展示了过去将来完成时的用法：
- 过去的某一时刻之前已经完成的动作：
- She said that by that time yesterday, she would have finished her assignment.（她说截至到昨天的那个时刻，她已经完成了作业。）
- By the end of last week, they would have traveled to three different countries.（截至上周末，他们已经去了三个不同的国家。）
- 强调在过去某一时刻之前完成的状态：
- I found out that by the time of the meeting, he would have lived in this city for ten years.（我发现在会议时，他已经在这个城市住了十年。）
- She mentioned that she would have known him for a decade by the time they met again.（她提到到他们再次见面时，她已经认识他十年了。）
- 过去某一点之前完成的计划或意图：
- He told me that by the time I arrived, he would have prepared dinner.（他告诉我，当我到达时，他已经准备好晚饭了。）
- When he came back, I knew he would have read the entire book.（当他回来时，我知道他已经读完整本书。）
过去将来完成时用来表示过去的某一时刻之前已经完成的将来动作，强调动作在过去某一点的完成状态。
表示从过去某点看将来某时前会已发生的事。
* I thought you‘d have left by this time. 我想这会儿你已经走了。
* I guessed that Helen would have told her something. 我猜海伦会告诉她一些情况的。
* I thought he would have finished his homework before Friday. 我认为他会在星期五之前完成他的功课。
* She said she‘d have finished her exams by then. 她说那时她会已经考完试了。
* If she hadn’t married, she would probably have achieved more. 如果她没结婚，成就或许会更大。
