pollution 可数吗

　　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。