—It seems that you know Dr. John very well. —Of course we together for five years in the

问题补充：

—It seems that you know Dr. John very well.

—Of course, we together for five years in the 1990s.

A. have worked

B. had worked

C. are working

D. worked

答案：

A. have worked

B. had worked

C. are working

(答案→)D. worked

解析：答案：D考查时态。一般过去时陈述过去的事实。