can 和 could 的区别
问题描述：
can 和 could 的区别
If it were not for the fact that she_____sing,Iwould invite her to the party.
A.couldn't B.shouldn't C.can't D.might not
正确答案是C.我选的是A.请问为什么?搞不太懂.
什么时候只能用can,而不用could?
答
PS这是虚拟语态,用C有它的理由（事实上她不能是任何时候都不能事实型,而且也不需要后退时态等）这里是语法问题,不是一般的can和could区别.
I hope this may help you,but I am not sure.