将来完成时(future perfect tense)表示在将来某一时间之前所完成的动作。它的形式由shall(第一人称)或will(第二、三人称)加have再加过去分词所构成。美国英语一律用will。
将来完成时的用法
将来完成时表示在将来某一时间以前已经完成的动作。如：
By the end of this week， I shall have finished the book.到本周末，我将读完这本书。
By this time tomorrow they will have repaired the machine.明天这时候，他们将修好这台机器。
The children will have gone to sleep by the time We get home.到我们回家时，孩子们将已睡了。
When you come tonight at eight o'clock，I shall have written my paper.你今晚八点钟来时，我将会写完文章了。
By next year our teacher will have taught English for twenty years.到明年我们的老师将已教二十年英语了。