thecitieshavebeenchangingquicklythesedays.abouttenyearsago,cityisaplacewhereyoucanseetreesandflowerseverywhere.therewerebuses,bikesandcarsrunningonroads,butyourarelysawthetrafficjams.theskywasblueandtheairwasclearandfresh.inthecountrysidetheenvironmentwasevenbetter!however,withthefastdevelopingindustriesandincreasingpopulation,moreandmorepeoplehavemovedintocitieswhichhasbroughttoomuchwastesintotheland,airandwater.now,theclearblueskyisrarelyseen,andtheairistotallyruined.wecallthemistyandgreyair"smog",whichmeansitiscomposedofsmokeandfog.peopleareestillrushingintocities,butwecouldnevergobacktoformerdays.