—Car prices have been going down sharply in the last 20 years.—Its not surprising because

问题补充：

—Car prices have been going down sharply in the last 20 years.

—Its not surprising because the law of market the price of a product.

A. is controlling

B. controls

C. has controlled

D. controlled

答案：

A. is controlling

(答案→)B. controls

C. has controlled

D. controlled

解析：B句意：“汽车的价格在过去的急剧下降。”“这一点也不奇怪，因为市场规律决定产品的价格。”“市场规律决定产品的价格”说的是一个客观事实，因此用一般现在时。