I can't understand why he __ have said that it was my fault. A could B might C should D would

问题描述:

I can't understand why he __ have said that it was my fault. A could B might C should D would

A本来能做成的(却没做成)
B可能已经
C本应当做某事
D过去将来完成时(可用于虚拟句,表示与过去的事实相反);过去将来完成时(表示在过去某一时间对将来某一时刻以前所会发生的动作)