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来源: 于 2013-01-23 11:04:46 [博客] [旧帖] [给我悄悄话] 本文已被阅读：次

BJ was polluted 20+yrs ago whenever there was a sandstorm. 10+ yrs ago it is hard to see the sun. The sun looks like a moon. Now one may not see the sun at all.

What are the causes? What measures can be taken to control the pollution.