Qhov tseem ceeb tshaj plaws yog kuaj cov khoom. Nov yog thawj qhov xwm txheej rau xaiv cov khob. Cov khoom faib ua cov khoom tseem ceeb ntawm cov menyuam' s khob dej yog: khob khob, khob khob, khob iav thiab khob khob khob, thiab cov ntaub ntawv yas tau muab faib ua cov khoom siv hauv PC, PP khoom siv, PES khoom, TRITAN khoom, thiab TR55 cov khoom siv. Txog rau tam sim no, cov menyuam yaus cov taub tshaj plaws' s khob dej khob yog cov pas hlau tso kua txiv thermos khob siv rau lub caij nplooj zeeg thiab caij ntuj no thiab khob yas siv thaum lub caij ntuj sov. Tab sis nws yuav tsum raug sau tseg tias tsis hais hom twg yuav tsum yog cov khoom noj-qib cov khoom siv, nws yuav tsum tau sim thiab ntawv pov thawj los ntawm lub koom haum muaj ntawv tso cai.
