问题
单项选择题
—I wonder why Mr. Green looks quiet in class.
—I'm not sure, but he（）a small accident driving here.
A. could have
B. might have
C. might have had
D. must have had
答案
参考答案：C
解析：
根据上下文语境可知，答话人的意思是对过去事情的推测，由于不肯定的语气I'm not sure，所以应选might have had...意思为：很可能在他开车来这儿的时候，发生了一起小事故。故选C。