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
과학사는 인류의 발전에 중요한 역할을 해왔다.gwahaksa-neun inryu-ui baljeon-e jungyohan yeoghal-eul haewassda.The history of science has played an important role in the development of humanity.