Tsis tas li ntawd xwb. Ntau lub tsev pheeb suab niaj hnub no muaj cov khoom siv zoo nkauj xws li chav dej hauv chav, da dej kub, cov ntaub pua chaw pw zoo, thiab lub lawj ntiag tug. Txawm hais tias cov tsev so yuav muaj cov chaw ntxiv xws li pas dej ua luam dej lossis chaw noj mov loj dua, cov tsev pheeb suab muab kev nplij siab zoo sib xws nrog kev sib txuas zoo dua rau xwm.