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
시계의 도파구는 시간을 정확하게 측정하는 데 중요합니다.sigyeui dopagu-neun sigan-eul jeonghwagage cheugjeonghaneun de jungyohamnida.The escapement of the clock is important for accurately measuring time.