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
횡격막은 호흡을 조절하는 중요한 근육입니다.hoenggyeokmak-eun hoheub-eul jojeolhaneun jungyohan geun-yug-imnida.The diaphragm is an important muscle that regulates breathing.