问题补充：
When we first met on a train in 2000, we both felt immediately that we each other for years.
A. know
B. had known
C. know
D. have known
答案：
A. know
(答案→)B. had known
C. know
D. have known
解析：在2000年我们第一次相遇时,我们都立刻感到我们互相已经认识了好几年.通过句意分析可以知道,我们在2000年以前已经认识了,所以时态应为过去完成时.
