-- of the population of the city workers? --About 60 percent. A. What; isB. What; areC. Ho

问题补充：

-- of the population of the city workers?

--About 60 percent.

A. What; is

B. What; are

C. How much; is

D. How much; are

答案：

A. What; is

B. What; are

C. How much; is

(答案→)D. How much; are

解析：考查population的用法。对人口“提问”，用what来问总人口；how much问的是“多少（比例）”。句意“这个城市人口的多少比例是工人？”“大约60%。”population作主语，谓语用单数，但是指具体的人数时，谓语用复数。故选D。