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
양병설은 두 가지 상반된 개념을 설명하는 데 사용됩니다.yangbyeongseol-eun du gaji sangban-doen gaenyeom-eul seolmyeonghaneun de sayongdoemnida.The theory of duality is used to explain two opposing concepts.