Cov yas ntim khoom yas yog ib hom ntawm cov khoom siv rau khaws cia ntau qhov chaw. Nws muaj cov yam ntxwv ntawm acid thiab alkali tsis kam, roj stain tsis kam, tsis muaj tshuaj lom thiab tsw ntxhiab, yooj yim los ntxuav, ua kom huv si, thiab yooj yim los tswj. Raws li cov tsos, siv sijhawm, nqa lub peev xwm thiab ...
Nyeem ntxiv