1.TYT muaj peb tus kheej "kev sim kuaj qhov chaw" tuaj yeem ua tau raws li txhua yam ntawm kev kuaj xyuas, kom paub meej cov khoom zoo.
2. Cintrol zoo nruj me ntsis.Qhov thawj dhau yog kev soj ntsuam zoo ntawm cov kab ntau lawm, Qhov thib ob hla yog tag nrho cov tshuaj xyuas ntawm cov khoom zoo.
3. Txhawb kev xeem thib peb, xws li SGS, BV, ect.
