Cov yam ntxwv tseem ceeb yog kev yaig zoo, qhib me me thiab kaw lub zog, hloov tau yooj yim, qauv luv, thiab lub teeb yuag. ltis tshwj xeeb tshaj yog tsim rau kev txiav thiab kho cov kav dej nrog qhov kub thiab txias, cov plua plav loj hauv nruab nrab, thiab kev ua haujlwm nquag. Cov kab no ntawm cov plua plav thiab roj npauj npaim li qub muaj ntau txoj kev tsav tsheb thiab tuaj yeem hloov mus rau qhov sib txawv ib puag ncig. Lawv tau siv dav hauv cov pa roj, cov roj hluav taws xob, cov kav dej hauv huab cua thiab kev tiv thaiv ib puag ncig thiab kev tshem tawm cov plua plav hauv cov khoom siv hluav taws xob, tshuaj lom neeg kev lag luam, tshuab, cement, hluav taws xob thiab lwm yam lag luam.
