Muab qhov sib txawv ntawm cov txheej txheem txheej txheem txheej txheem (xws li txheej txheej txheej, viscosity, substrate variation, kub, huab cua sib tov, kis kab mob, evaporation, av noo, thiab lwm yam), txheej txheej teeb meem feem ntau tuaj yeem tshwm sim.Cia peb saib qee qhov teeb meem uas tuaj yeem tshwm sim thaum ...
Nyeem ntxiv