1. Kev ua xim xim: lub Hoobkas kho vajtse siv cov xim pleev xim thaum tsim cov khoom lag luam loj, thiab cov khoom siv hlau raug tiv thaiv los ntawm xeb los ntawm kev ua xim, xws li cov khoom siv niaj hnub, cov khoom siv hluav taws xob, cov khoom siv tes ua, thiab lwm yam. 2. Electroplating: Electroplating kuj yog ib qho ntawm lub...
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