Sib tov tshuab
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Muaj peev xwm ntau lawm Ob Chav Ncej Tov Khoom
Ob Chav Ncej Tov Tshuab yog siv rau kev sib tsoo cib raw cov ntaub ntawv thiab sib tov nrog dej kom tau cov khoom sib xyaw ua ke, uas tuaj yeem txhim kho kev ua tau zoo ntawm cov ntaub ntawv raw thiab zoo heev txhim kho cov tsos thiab molding tus nqi ntawm cib. Cov khoom no yog tsim rau av nplaum, shale, gangue, ya tshauv thiab lwm yam khoom siv dav siv.