Cov tub ntxhais kawm lub hom phiaj yog tsim kom muaj ntau qhov chaw noj qab haus huv uas cov tub ntxhais kawm tuaj yeem muaj kev nyab xeeb thiab txhawb nqa. Qhov chaw no kuj yog ib qho chaw uas lawv tuaj yeem nrhiav tau cov peev txheej, cov khoom siv tu cev, ua kom muaj kev thaj yeeb nyab xeeb, mus koom kev cob qhia kev tiv thaiv, so thaum xav tau, thiab ntau ntxiv.