Black smoke from some big chimneys of factories and mines in Peking, Shanghai, Hangchow and Changchun has ceased. Work on cutting air pollution from factory and mine smokestacks began several years...
Please login first!
Black smoke from some big chimneys of factories and mines in Peking, Shanghai, Hangchow and Changchun has ceased. Work on cutting air pollution from factory and mine smokestacks began several years...