I hear you have an experience in the Roya1 Air Force. Is that true？- Yes. I in the

问题补充：

--- I hear you have an experience in the Roya1 Air Force. Is that true？

--- Yes. I in the Royal Air Force for six years.

A. served

B. had served

C. joined

D. have joined

答案：

(答案→)A. served

B. had served

C. joined

D. have joined

解析：此题考查的是学生对动词时态及是否延续动词的掌握。