While along the street I met an old friend of mine.A. I walking B. was walkingC. I am wa

问题补充：

While along the street, I met an old friend of mine.

A. I walking

B. was walking

C. I am walking

D. walking

答案：

A. I walking

B. was walking

C. I am walking

D. walking

解析：：考查状语从句的省略。当状语从句的主语和主句的主语一致的时候，可以把状语从句的主语和系动词一起省略。本题省略了Ｉwas.句意：当我在街道上走的时候，我遇见了一个老朋友。故D正确。