--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
网友回答
A. have polluted
B. is being polluted
C. has been polluted
(答案→)D. have been polluted
解析：考查主谓一致。本题属于主谓一致里特殊用法large quantities of的后面既可以接可数名词也可以接不可数名词，谓语动词都使用复数形式。句意：—为什么这个湖闻起来很臭？—因为大量的水都已经被污染了。根据句意说明使用被动语态。而且是已经被污染了，也要使用现在完成时的形式。故D正确。