请问will have done 用法

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