Cov txheej txheem tsim khoom turf feem ntau suav nrog cov kauj ruam hauv qab no: 1.Xaiv cov ntaub ntawv: Cov khoom siv tseem ceeb rau cov khoom siv dag zog muaj xws li cov khoom siv hluavtaws (xws li polyethylene, polypropylene, polyester, thiab nylon), hluavtaws resins, tshuaj tiv thaiv ultraviolet, thiab cov khoom ntim. . Siab...
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