if的用法,英语选择题辨析,

if的用法,英语选择题辨析,-- I don't know if she__________.-- She'll come here if it_______.A.comes;won't rainB.comes;doestn't rainc.will come; won't raind.will come;doesn't rain请问在这里if什么时候后面加一般现在时,什么时候加will?