Question

By next Sunday she ( )with us for three weeks. A.will have stayed B.will has stayed

选哪一个？另一个为什么不选？

Answer 1

将来完成时

　　1.概念：在将来某一时刻之前开始的动作或状态

　　2.时间状语：by the time of;by the end of+时间短语（将来）;by the time+从句（将来）

　　3.基本结构：be going to/will/shall + have done

　　4例句:By the time you get back,great changes will have taken place in this area

先A
has 跟在be going to will shall 后面变动原形即have

Answer 2

选A,will后面加动词原形。

追问

,will后面加动词原形，为什么？依据是什么？

Answer 3

选A，

追问

为什么？

追答

WILL后面加动词原形

追问

只听过情态动词加原形啊，可will不是，怎么解释？