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
탄화물은 금속의 경도를 증가시키는 데 사용됩니다.tanhwamul-eun geumsog-ui gyeongdo-reul jeungga-sikineun de sayongdoemnida.Carbides are used to increase the hardness of metals.