I in the street when I met an old friend of mine yesterday.A. walkedB. was walkingC. has

问题补充：

I in the street when I met an old friend of mine yesterday.

A. walked

B. was walking

C. has walked

D. had walked

答案：

A. walked

(答案→)B. was walking

C. has walked

D. had walked

解析：前半句是主句，沿街散步这个动作是延续性的动作，因而我们用过去进行时。后半句这个时间状语从句的动作，遇到，是个短暂性动作。因为when I met an old friend of mine yesterday.用的是过去式。故排除C。句意：当我看到我的一个老朋友的时候，我正在沿着街道散步。故选B。