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
열평형을 유지하는 것은 에너지 효율성을 높이는 데 중요하다.yeolpyeonghyeongeul yujihaneun geoseun enoji hyoyulseong-eul nopineun de jungyohada.Maintaining heat balance is important for increasing energy efficiency.