I'm not sure if she____tomorrow.If she ___tomorrow.

问题描述:

I'm not sure if she____tomorrow.If she ___tomorrow.
I will call you at once.
A.comes,will come B.will come,comes
C.will come,will come
有两个if不知怎么选,请说明理由,

选B.
译文:我不确定她明天是否来.如果她明天来.
前句的if是“是否”,是什么时态就用什么时态.
后句的if是“如果”,引导条件从句,要用一般现在时.