Yas yog cov khoom siv hluavtaws lossis cov khoom siv ntuj tsim, piv rau cov hlau, pob zeb, ntoo, cov khoom yas muaj qhov zoo ntawm cov nqi qis, plasticity, thiab lwm yam. Cov khoom siv yas yog siv dav hauv peb lub neej, kev lag luam plastics kuj muaj txoj haujlwm tseem ceeb hauv ntiaj teb. hnub no. Nyob rau hauv xyoo tas los no, som ...
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