The population of the city from less than half a million in 1949 to over two million.A. ha

问题补充：

The population of the city from less than half a million in 1949 to over two million.

A. have increased

B. has increased

C. have improved

D. has improved

答案：

A. have increased

(答案→)B. has increased

C. have improved

D. has improved

解析：increase 数量方面的增加；improve 状况方面的改进。