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
중력기를 사용하여 우주에서 실험을 진행했습니다.jungnyeokgireul sayonghayeo ujueseo silheom-eul jinhaenghaessseubnida.We conducted experiments in space using a gravity device.