请看例句：

He has finished writing his novel. 他已写完了他的小说。

He had finished writing his novel by the end of last year. 去年年底他就写完他的小说。

He will have finished writing his novel by the end of next year. 到明年年底他就会写完他的小说了。

与一般现在时代替一般将来时一样，在表示时间或者条件的状语从句，通常要用现在完成时来表示将来完成时，而不能直接使用将来完成时：

I will go with you when I have finished my work. 等我完成工作之后我就同你去。

若不强调动作的完成(且不至于引起歧义)，有时也可用一般现在时：

I will go with you when I finish my work. 我完成工作后就同你去。

四、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.(www.yygrammar.com) 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。