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
통시적 분석은 역사적 변화를 이해하는 데 중요하다.Tongsijeok bunseogeun yeoksajeok byeonhwareul ihaehaneun de jungyohada.Diachronic analysis is important for understanding historical changes.