Since the opening and reform policy Chinaa boom in its economy.A. enjoysB. has been enjoy

问题补充：

Since the opening and reform policy, Chinaa boom in its economy.

A. enjoys

B. has been enjoying

C. enjoyed

D. having enjoyed

答案：

A. enjoys

(答案→)B. has been enjoying

C. enjoyed

D. having enjoyed

解析：考查时态。句意：自从改革开放政策以来，中国一直经济繁荣。用现在完成进行时态表示的是从过去到现在还要持续下去。根据题意中国的经济还要繁荣下去。故选B。