请问will have done 用法请问 they will have finished 和 they will finish 有什么区别?

请问will have done 用法请问 they will have finished 和 they will finish 有什么区别?
请问will have done 用法
请问 they will have finished 和 they will finish 有什么区别?

请问will have done 用法请问 they will have finished 和 they will finish 有什么区别?
will have done是将来完成时,强调在某一时间的时候.已经.完成
标志词有bythe end of this(next) term\week\year\month,在今、这（下一个）学期\周\年\月之前（某人已经做完了...）,比如
They will have finished the homework by the end of the week.到那时一定已做完
而will do是一般将来时,只强调动作即将发生,却没有一定会完成的意思（这就是与将来完成时最大的区别）
They will do their homework this year.不一定做完

they will have finished 在某时间前可能已经完成
they will finish 必须到某时间才可完成

前者是完成式,强调动作结果
后者是一般式,强调动作本身.