Lub tsheb maus taus cov tuam txhab hais tias thaum siv tsheb rims, muaj peb lub ntsiab lus uas tsis tuaj yeem tsis quav ntsej:
Ua ntej, them sai sai rau cov txheej txheem: cov tsos ntawm cov khoom lag luam qis dua qee zaum zoo, tab sis vim yog cov txheej txheem tsis zoo, cov kab nrib pleb, cov xuab zeb qhov, slag suav nrog, burrs lossis pob tawg yog qhov tshwm sim. Yog hais tias lub taub hau kheej kheej yog zawm thiab txawv txav, nws yuav ua rau lub ntsaws ruaj khov thiab laum tawm thaum siv, ua rau cov cua nkag mus, cov roj tawm thiab dej paug.
Thib ob, them nyiaj rau xoob: qhov sib xyaw ntawm ob lossis ntau qhov chaw, qhov yuav tsum tau lo, txuas lossis nias kom haum, yog li tsis txhob xoob xoob.
Qhov thib peb, them sai sai rau cov xim pleev xim: cov tub luam tsis zoo yuav siv cov txheej txheem yooj yim ntawm cov seem, xws li khawb, dismantling, sau ntawv, thauj khoom, tha xim, thiab lwm yam, ces ua txuj tias 'khoom tsim nyog' rau muag, thiab tom qab ntawd tev tawm ntawm xim xim kom pom cov xim qub.
