—Car prices have been going down sharply in the last 20 years.—It's 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 考察动词时态。由语境可知，市场规律控制商品价格，这是一个客观真理，因此应该使用一般现在时。故B正确。