题目内容：

6 Three million tons of coal ________ every year in the city.
A is exploited B are exploited C had exploited D have exploited
为什么选B 不是该用完成时吗?

优质解答

..首先,要注意 "every year "...因为事 every year ,所以不能用完成时,而且,即使要用完成时的话,后面也要捷been,表示被动,即have/had been exploited