Great changes in the small city in the last 20 years.A. have taken placeB. took placeC. ha

问题补充：

Great changes in the small city in the last 20 years.

A. have taken place

B. took place

C. had taken place

D. are happening

答案：

(答案→)A. have taken place

B. took place

C. had taken place

D. are happening

解析：考查时态：时间是in the last 20 years，和现在完成时连用，句意是：在过去的里，这个小镇已经发生了巨大的改变。选A。