Guessariddle(猜谜语)
Youcanseerailways,buttherearenotrainsonthem.Youcanseeroads,buttherearenobusesorcarsortrucksorjeepsonthem.Youcanseerivers,buttherearenoshipsorboatsonthem.Youcanseemountains,buttherearenotreesorflowersonthem.Youcanseecitiesandtowns,buttherearenopeopleorhousesinthem.Whatisit?
It's_