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
지치주의는 사람의 피로를 이해하는 데 중요한 개념입니다.jichijuui-neun saram-ui piro-reul ihaehaneun de jungyohan gaenyeom-imnida.Fatigue theory is an important concept in understanding human fatigue.