Lub valve belongs rau cov cuab yeej siv tshuab lossis khoom siv
Li qub tsis yog cov khoom siv, tsuas yog cov kav dej, tab sis thaum lawv yog cov khoom tshwj xeeb, lawv tsis yog cov qauv loj thiab nruab nrab li qub.
Kev faib cov li qub thiab cov khoom siv tsis sib xws hauv ntau qhov chaw (xws li kev siv nyiaj txiag engineering, cov peev nyiaj ruaj khov, kev tswj xyuas qhov project engineering thiab lwm yam lag luam).
