pollution
n. 污染；污染物
pollution在指污染种类时可数，如果单只一种，就不可数。
例句
Steps are to be taken to abate pollution.
应该采取措施减少污染。
Pollution is still very much a live issue.
污染仍然是目前非常让人关注的问题。
Cars cause pollution, both smog and acid rain.
汽车引起污染，既有烟雾又有酸雨。
The level of pollution in the river was falling.
该河流受污染的程度其时正在降低。
