將來完成時的主要用法歸納整理
1. 表示將來完成
即表示到將來某個時間爲止勢必會完成或預計要完成的動作。如：
Maybe by then you will have changed your mind. 也許到時候你已經改變主意了。
“You'll have finished by tomorrow.” “I wish!” “你到明天就完成了。”“但願如此! ”
I hope I'll have finished the work by the end of the month. 我希望我這個月底能完成工作。
Demand for cars in the developed world will have reached saturation point within 20 years. 不出20年，已發展國家的汽車需求將達到飽和。
Planning so far ahead makes no sense—so many things will have changed by next year. 提前這麼久就計劃並不明智——到明年，許多事情都會發生變化。
2. 表示動詞的持續
即表示某種狀況將一直持續到說話人所提及某一將來時間。如：
We will have been married a year on June 25th 到6月25日我們倆結婚就滿1年了。
By this time next week, I will have worked for this company for 24 years. 到下星期此刻，我已經爲該公司幹了24年了。
3. 表示推測
即表示根據某情況作出的推測。如：
That will have been Roland. He said he'd be back at 7. 準是羅蘭，他說他7點鐘回來。
There will have been a definite result before Friday. 星期五以前將肯定會有結果。
