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
현실층은 우리가 경험하는 세계의 구조를 설명합니다.hyeonsilcheungeun uriga gyeongheomhaneun segyeui gujoreul seolmyeonghamnida.The layer of reality explains the structure of the world we experience.