Lub qhov rooj hluav taws tau muab faib ua ib-nplooj, ob-nplooj, puv-board, thiab ib nrab-iav pawg. Lub sijhawm hluav taws kub ntawm lub qhov rooj hluav taws muaj feem xyuam rau cov khoom siv, yog li nws yuav tsum tau nruab thiab siv rau hauv qhov chaw sib txuas thaum yuav khoom. Txais tos kom sab laj peb.