阅读下面短文,用适当的关系代词填空(就是who,that那些的)
ManyAmericansenjoycamping.EachsummermillionsofAmericansdrivetothecountrysidewheretheyfindplacestocamp.Thenationalparks1._____freshair,clearlakesandthickforestsareattractivetocampersarefavouritecampingplaces.Campershike,swimandfish.Somecampershavetrailers2._____theydriveorpullbehindtheircampsites.Trailersarelikehousesonwheels.Theyhavemanyconveniences3._____peoplehaveintheirhomes,suchaselectricityandhotwater.Butmostcampersdon'thavetrailers.Theycampintentsintheircampsites.Campers4._____areintentsdon'thavetheconveniences5._____campersintrailershave.Tentcampersenjoyaverysimplelife.