1. Npaj cov ntaub ntawv raw Cov ntaub ntawv raw ntawm cov ntaub pua tsev muaj xws li cov ntaub ntawv tseem ceeb thiab cov ntaub.Thaum npaj cov khoom siv raw, nws yog ib qho tsim nyog yuav tsum tau yuav cov ntaub ntawv sib xws raws li cov khoom tsim tsim.Feem ntau cov khoom tseem ceeb ntawm cov ntaub pua plag hauv pem teb muaj xws li roj hmab, PVC, EVA, thiab lwm yam, thiab ...
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