Now,itmaybedifficulttopredictthefuture,butmanypeoplebe...
问题详情： Now,itmaybedifficulttopredictthefuture,butmanypeoplebelievethatwewillliveonMarsbytheyear2100.Ourownplanet,Earth,isbecomingmoreandmorecrowdedandpolluted.Well,whatproblemswillweneedtosolvebefo...