6、oGrandeRiver formsanaturalboundarybetween Mexico and theUnitedSates.里奥格兰德河是美国和墨西哥之间的天然界河。9.themostimportantlakesintheUnitedStatesare theGreatLakes.They areLakeSuperior,whichisthe largestfreshwaterlakeintheworld, LakeMichigan,theonlyoneentirelyintheUS, LakeHuron,LakeEi
7、reandLakeOntario.TheyarelocatedbetweenCanadaandtheUnitedStatesexceptLakeMichigan.美国最重要的湖泊是五大湖:苏必利尔湖,密歇根湖,休伦湖,伊利湖,安大略湖。除密歇根湖外均位于美国和加拿大之间。其中,苏必利尔湖为世界最大淡水湖,密歇根湖完全在美国境内。10.Manyfactorsbesideslatitudeinfluence the climateintheUnitedStates.Perhapsthemostimportantforcesare th