Daim ntawv thov: Tsim nyog los npaj cov khoom siv yas, sib tov roj hmab los yog ua kom kub refining thiab molding.
Daim ntawv thov:Haum rau kev sim siv los npaj cov khoom siv yas, sib tov roj hmab los yog ua kom kub refining thiab molding.