We first met on a train in 2010，but we both felt immediately that we each other for years.
A. knew
B. have known
C. had known
D. know
网友回答
A. knew
B. have known
(答案→)C. had known
D. know
解析：
根据题干所提供的信息，首先弄清说话者在谈论过去的事情，因此用过去时，排除B、D两项，然后考虑动词know在felt之前，即过去的过去，因此用过去完成时。