More and more people have realized that we won’t have cleaner water to drink unless someth

问题补充：

More and more people have realized that we won’t have cleaner water to drink unless something soon.

A. is done

B. was done

C. will be done

D. to be done

答案：

(答案→)A. is done

B. was done

C. will be done

D. to be done

解析：句意：越来越多的人意识到如果我们不马上采取措施我们就不会有干净的饮用水。在unless 引导的从句中，something 是主语，它与谓语动词do 构成被动的关系，所以这里要使用被动语态。而且unless 从句中应用一般现在时，故选A。