【题目】—Why does the lake smell terrible?
—Because large quantities of water .
A. have polluted B. have been polluted
C. is being polluted D. has been polluted
在线课程【答案】B
【解析】
试题分析：B；考查性数一致。根据分析，可知时态用现在完成时表示一个结果。主语是large quantities of water是一个复数形式，所以谓语动词也应该用复数形式，水污染应该是被污染，所以谓语还应该体现被动语态。句意：——为什么湖水这么难闻？——因为大量的水被污染了。故选B