SinceJanuary2013,manycitiesinChinahaveseenalotoffoggyda...
问题详情：SinceJanuary2013,manycitiesinChinahaveseenalotoffoggydays.InBeijing,onlyfivedaysinJanuarywerefreeofsmog(雾霾).What’sthedifferencebetweenfogandsmog?Accordingtoscientists,fogismadeupoftiny(微小...