Black Friday: lifetime access is on a special offer in the app, until November 30. Black Friday: special offer on lifetime access, until November 30. Download
철도사업은 국가 경제에 중요한 역할을 합니다.cheoldosahoeun gukga gyeongje-e jungyohan yeoghal-eul hamnida.The railroad business plays an important role in the national economy.