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
프라운호퍼선은 별의 스펙트럼을 분석하는 데 중요한 역할을 합니다.peuraunhopeoseun-eun byeol-ui seupekteureom-eul bunseoghan-eun de jungyohan yeoghal-eul hamnida.Fraunhofer lines play an important role in analyzing the spectrum of stars.