Ntau qhov chaw, txawv tus yam ntxwv, thiab lwm yam.
Ntau qhov chaw: cov ntaub ntawv nkauj xwb los ntawm qhov xwm txheej thiab yuav tsum tau muab sau thiab ua tiav, thaum cov khoom siv rov ua dua los ntawm cov khoom siv thiab cov ntaub ntawv pov tseg, uas feem ntau yuav tsum tau rov ua dua ua ntej lawv tuaj yeem siv dua.
Cov yam ntxwv sib txawv: cov khoom siv raw muaj cov khoom ruaj khov thiab zoo, thaum cov khoom siv rov ua dua txo cov peev txheej, tab sis nws qhov zoo thiab kev ua tau zoo yog qhov nyuaj rau lav, thiab nws muaj cov khoom tsis ruaj khov thiab nyuaj.
