Ua los ntawm cov khoom siv hluav taws xob hloov tau yooj yim, cua sov ceev thiab txav tau yooj yim
cia. - Siv cov tawv zoo hauv pem teb, hnav-tiv taus thiab khawb resistant, tuaj yeem siv tau txhua lub sijhawm yam tsis txhob hle koj nkawm khau.
Qhov hloov pauv tau tshwm sim los ntawm ib kauj ruam, tsis tas yuav khoov.