Question

4. We first met on a train in 2007. We both felt immediately that we       (know) each other for years.

Answer 1

4. had known考查時(shí)態(tài)。根據(jù)for years可知，應(yīng)使用完成時(shí)。主句時(shí)態(tài)為一般過去時(shí)，從句時(shí)態(tài)應(yīng)與之呼應(yīng)，故使用過去完成時(shí)。