Sincethebeginningoftheyear,smoghascoveredpartsofNorthCh...
问题详情：Sincethebeginningoftheyear,smoghascoveredpartsofNorthChina.InJanuary,Beijingsawonlyfivedayswithoutsmog.TherisingPM2.5readingsterrifiedmanypeople,andsomehealthexpertssaidthatwheneverthesmoggets...