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
계층론은 사회 구조를 이해하는 데 중요한 개념이다.Gyecheungnon-eun sahoe gujo-reul ihaehaneun de jungyohan gaenyeomida.Hierarchical theory is an important concept for understanding social structure.