单选题 ______"his second heart attack if he hadn't smoked?" "He might not have."
A. Would he have had B. Would he have
C. Had he had D. Were he to have

【正确答案】 A
【答案解析】[解析] 本题为虚拟过去时或叫非真实条件句过去时，条件句用过去完成时，作出与过去事实相反的假设，主句谓语用would/could/might have+动词的过去分词。