Ua Ntej: Hauv cov txheej txheem ntawm cov thawv ntim cov yas, nws yog qhov yuav ua tau tias cov ntsia hlau ntswj yuav raug txiav tawm, ua rau cov ntsia hlau ua cov dej khov thiab cov roj hluav taws xob tsis sib haum. Thaum lub sij hawm txheej txheem kev txhaj tshuaj, kev kub ntxhov ntawm cov khoom nyoos yuav hloov.
Thib ob: Qhov laj thawj yuav yog vim tias cov khoom siv tau muab khaws cia rau ntev dhau lawm, cov khoom siv kuj ntxooj, thiab qee qhov ya raws.
