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
열곡은 지구의 지각이 갈라져 형성된 지역입니다.Yeolgok-eun jigu-ui jigak-i galajyeo hyeongseongdoen jiyeog-imnida.A rift valley is an area formed by the splitting of the Earth's crust.