1. Resistance rau nruab nrab qhov hnyav nce qhov ntsuas cov khoom tiav tuaj yeem ua qauv, tsau rau hauv ib lossis ob peb lub xov xwm xaiv, hnyav tom qab qee qhov ntsuas kub thiab lub sijhawm, thiab hom khoom tuaj yeem txiav txim siab raws li qhov hnyav hloov pauv thiab qhov hloov pauv hardness. .Piv txwv li, immersed hauv ...
Nyeem ntxiv