Feem ntau, ib txwm ua tib zoo saib xyuas cov roj qib hauv cov iav, muab cov roj lubricating txaus, thiab xyuas kom meej tias cov roj ntshiab huv, thiab hloov cov roj tshiab tsis tu ncua (rau lub hlis lossis ib xyoos). Cov tshuab hluav taws xob, nyob ib puag ncig cov khoom siv hluav taws xob, tsis tso cai rau khaws cov khoom siv, cov khoom siv los yog cov roj hluav taws xob uas rhuav tshem cov rwb thaiv tsev. Nyob rau tib lub sijhawm, nws yuav tsum tau hais kom siv cov khoom siv hluav taws xob los ua haujlwm hauv qhov chaw qhuav. Yog tias nws nyuaj rau kev tiv thaiv, cov khoom siv tiv thaiv noo noo yuav tsum tau ntxiv.


