Cov khoom no tsuas yog cov neeg siv khoom cov ntaub ntawv tso tawm, tsis yog muag, thiab siv xwb.
Manually thiab cia li kaw lub qhov rooj qhib hluav taws ib txwm;Saib xyuas cov xwm txheej ntawm ib txwm qhib lossis ib txwm kaw qhov rooj hluav taws hauv lub sijhawm, thiab tshaj tawm thiab tso saib nws.