tom might have come to school in time for the lecture()

tom might have come to school in time for the lecture()
A if he got up earlier B unless he had got up earlier
不是有句型是:当主句是S+might have done 从句就用If+S+had done
那A是不是差个had (if he had got up earlier)

原句的意思是：汤姆也许会及时赶到学校去听演讲.
A的意思是：如果他早点起床
B的意思是：除非他做点起床（unless=if not ,即为如果他没有早点起床）
按照语法来说,这是虚拟语气,所以应选A.不考虑意思,则如果要选B,此句应为tom would have come to school in time for the lecture unless he had got up earlier.因此应选A.