I ____ have been more than six years old when the accident happe

I ____ have been more than six years old when the accident happened.
A、shouldn't
B、couldn't
C、mustn't
D、needn't
【正确答案】：B
【题目解析】：【考点点击】本题考查情态助动词can的用法。【要点透析】当can表示对过去的推测时,应用其过去体 could。本句意为:那件事故发生时,我不可能已经六岁了。