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
등시의 곡선은 모든 점에서 같은 시간을 나타냅니다.deungsiui goksun-eun modeun jeom-eseo gateun sigan-eul natanabnida.The isochronal curve represents the same time at all points.