有关完成时的选择题

问题描述:

有关完成时的选择题
Jack and Jane ____ each other since they were children,so nobody was surprised to hear they were married.
A.had known B.have known C.were known D.knew
为什么不选B?
为什么不用现在完成时

过去完成时态,因为是小时候就了解对方,是小时候就完成的,所以要用过去完成时态!