必须是不可数啊
名词 n.[U]
1.污染,弄脏 We have freed the lake from pollution.
我们已经清除了该湖的污染.
The new law will reduce pollution of the rivers
这条新法规将会减轻河流的污染
2.污染物;污染地区
She was horrified by all the pollution on the beach.
她对海滩上的污染感到震惊.