Fromnowadays,theworldhavemoreandmorepeople,somebodysaythatwhenin2015,thepopulationoftheworldwillachieveabout70billion.Generaltosay,developingcountryhavemuchmorepopulationandincreasethantheadvancecountry.Thepopulationhavebrouhtmanyseniorsproblem,forexample:trafficjams,pollutionoftheenvironment,theresourcesarenotenoughforus,andsoon.Thepopulationsproblemistobecomethemostseriousprobelmoftheworlds.Therefore,controlthepopulationaretheoneofthebiggestproblemoftheworlds.终于写完啦!haha,希望对你有帮助了