Why didn't you remind him of the possible danger?

问题描述:

Why didn't you remind him of the possible danger?
But what ____ otherwise?He never listens to me.
A.could I do B.could I have done C.should I do D.must I have done

otherwise,此句使用虚拟语气.对现在的虚拟:would + do; 对过去的虚拟:would + have done.--Why did you leave without a word of warning to John?为什么你不教训一下约翰就走了?--But what could I have done ot...