定义：将来完成时是用在表示在将来某一时间以前已经完成或一直持续的动作。经常与before+将来时间或by+将来时间连用，也可与before或by the time短语引导的现在时的从句连用。
结构：“will have +过去分词”。如：
将来完成时：He will have solved the problem.
将来完成时的被动语态：The problem will have been solved by him.
二、将来完成的用法
1. 表示“将来完成”
即表示到将来某个时间为止势必会完成或预计要完成的动作。如：

When we get there, she’ll have gone to work.

我们到那里时她会已上班去了。

I expect you will have changed your mind by tomorrow.

我预料到明天你就会改变主意了。

2. 表示“持续”
即表示某种状况将一直持续到说话人所提及的某一将来时间。如：

We will have been married a year on June 25th.

到6月25日我们俩结婚就满1年了。

By this time next week, I will have been working for this company for 24 years.

到下星期此刻，我就已经为该公司干了24年了。

3. 表示“推测
即表示根据某情况作出的推测。如：

That will have been Roland. He said he’d be back at 7.

准是罗兰。他说他7点钟回来。

There will have been a definite result before Friday.

星期五以前肯定会有结果。

三、将来完成通常搭配的状语
1. 用作状语的介词短语

There will have been a definite result before Friday.

星期五以前将肯定会有结果。

By next Christmas we’ll have been here for eight years.

到下一个圣诞节，我们在这儿就住了整8年了

。

By now you will have guessed that I’m back in Ireland.

你现在应该已经猜出我回到了爱尔兰了。

By the end of next week, I will have been a teacher for 25 years

.

到下周末，我当老师就有25年了。

We’d better wait till 14 December. David will have had his exam by then, so he’ll be able to enjoy himself.

我们最好还是等到12月14日。到那时大卫就考完试了，这样他就能够玩得痛快。

2. 用作状语的从句

If I don’t run, the train will have left.

如果我不跑，火车就会开走了。

If he turns it down, he will have lost the moral high ground to the president.

如果他拒绝的话，就会把精神上的优势输给总裁。

If you finish this job as well, you will have done far more than I expected.

假如你将这项工作干完的话，那你会干得比我预料的要多了。

If there was any scandal in that company, you can be sure that Bobby will have clocked it.

那家公司有任何丑闻，博比肯定会知道。