单选题 If we ______ sooner, we might have got there.
A. started B. had started
C. would have started D. start

【正确答案】 B
【答案解析】这是一个表示与过去事实相反的假设。这种虚拟形式一般是：从句谓语是过去完成时(had done)，主句谓语是would(should，could，might)+have done。