If you can't finish the work before Friday ,you may ________work on the weekend .

问题描述:

If you can't finish the work before Friday ,you may ________work on the weekend .
选项有4个:A:mustB:have C:have got toD:haven't to
为什么是选B啊C为什么就不可以啊?
B:have to
可是解释是这样说的:题中有情态助动词may,故ACD三项都不对

这里考的是情态动词的虚拟语气,may have done表示本来可以做而没做,句中解释为本来可以在双休日完成,其他选项完全不通,既不符合语法也不符合句意