After several years'efforts, the previously serious pollution in coal transportation system has been ba…

通过多年整治，使输煤系统原本严重的污染从根本上得到了控制。

youdao

After several years'efforts, the previously serious pollution in coal transportation system has been ba…

通过多年整治，使输煤系统原本严重的污染从根本上得到了控制。

youdao