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。