By the end of next week he will be back.改错.

问题描述:

By the end of next week he will be back.改错.

By 改成 At

By the end of next week, he will have been back.

By the end of next week,he will have been back.是这句,因为by the end of nest week是一个表将来完成时的时间状语,所以主句应用将来完成时.若有不解,请看语法中关于动词的时态与语态一章.