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
물방울은 공기 중의 수증기가 응결하여 형성된다.Mulbangul-eun gonggi jung-ui sujeunggi-ga eunggyeolhayeo hyeongseongdoenda.Water droplets are formed by the condensation of water vapor in the air.