Cov ntaub ntawv pov tseg ib txwm muaj, xws li ntoo thiab ua npuas dej, feem ntau raug pov tseg tom qab siv ib zaug xwb, ua rau muaj kev txhawj xeeb txog ib puag ncig thiab muaj pov tseg. Cov txheej txheem pov tseg rov siv dua, ntawm qhov tod tes, tuaj yeem siv ntau zaus, txo cov pov tseg thiab txhawb kev ruaj khov.
