Beijing a lot over the years. Now it has become one of the biggest in the world.A. chan

问题补充：

Beijing a lot over the years. Now it has become one of the biggest

in the world.

A. changes; cities

B. changed; city

C. has changed; cities

D. changed; cities

答案：

A. changes; cities

B. changed; city

(答案→)C. has changed; cities

D. changed; cities

解析：句意：这些年北京变化很多。现在它已经成为世界最大的城市之一。与时间短语over the years.连用时，用现在完成时。由one of来修饰时，后面用名词的复数形式。故选C。