Sincethebeginningoftheyear,smoghascoveredpartsofNorthCh...
問題詳情：Sincethebeginningoftheyear,smoghascoveredpartsofNorthChina.InJanuary,Beijingsawonlyfivedayswithoutsmog.TherisingPM2.5readingsterrifiedmanypeople,andsomehealthexpertssaidthatwheneverthesmoggets...