题目内容：

Did mary come to the party I do not know .she_wh
-Did Mary come to the party I do not know .she_while I was out.
-I do not know .She _while I was out.
A.may have come B must have come C might come D could come为什么不用D

优质解答

这是对过去的猜测,属于虚拟语气,答案应为A.
D could表示过去的能力,即过去有能力做某事,跟题意不符.
默文英语