6.Three million tons of coal ------ every year in the city.

Three million tons of coal ______ every year in the city。A。is exploited B。are exploitedC。had exploited\x05D。have exploited答案：B解析：coal用ton量词来修饰,Three million tons 为复数,所以谓语动词为复数。中文：在这座城市每年都会开发出三百万吨煤。