-Why does the Lake smell terrible?-Because large quantities of water. A. have pollutedB. i

问题补充：

-Why does the Lake smell terrible?

-Because large quantities of water.

A. have polluted

B. is being polluted

C. has been polluted

D. have been polluted

答案：

A. have polluted

B. is being polluted

C. has been polluted

(答案→)D. have been polluted

解析：考查动词时态，语态和主谓语一致。根据前一分句可知所填动词表示过去发生的动作对现在产生的影响，时态用现在完成时，动词与主语是被动关系，用被动语态。主语是large quantities of water，其中心词是quantities，是复数，谓语动词用复数，选D。