问题
选择题
________you were coming，I would have stayed at home.
A．If I know
B．Should I know
C．Had I known
D．If I should have known
答案
C
题目分析：句意：我要是知道你要来，我就呆在家里了。根据I would have stayed at home.可知是和过去相反的虚拟语气，从句用过去完成时，这里可以省略if，将had提前，所以选C。