问题
选择题
-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
答案：D
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。