Feem ntau ntawm cov kav dej yog qhov tsis pom kev engineering, peb tsis tuaj yeem nyob yam tsis muaj nws txhua hnub, ib zaug muaj teeb meem, tsis tsuas yog nrhiav tau yooj yim, thiab vim tias cov dej ntws tawm yog cov dej phwj tuaj, yooj yim ua rau muaj kev cuam tshuam tsis zoo rau cov tsev, nyob ib puag ncig. Yog li ntawd, nws yog ib qho tseem ceeb heev los xaiv cov kav dej zoo
Peb cov khoom, raws li lub teb chaws tus qauv tsim, ib tug xov tooj ntawm cov cim qhia tau zoo dua li lub teb chaws tus qauv yuav tsum tau, coj dawb kev tiv thaiv ib puag ncig, muab ib tug noj qab nyob zoo ib puag ncig. Kev ua tau zoo heev, tsis yooj yim rau tawg, ob qho tib si nruj thiab yoog raws, muaj zog cuam tshuam tsis kam, tsis yooj yim tawg