Tam sim no hais tias qhov kev txwv ceev ceev rau cov hnab yas tau nqis los, cov khw me me lossis cov khw muag khoom ntawm txoj kev yog cov hnab yas zoo tib yam, pp, pe, thiab lwm yam. Feem ntau hais lus, lawv nyuaj heev rau degrade lossis tsis degradable, ua raws li cov yas degradable. .Qhov sib ntxiv ntawm degradants rau yog li ...
Nyeem ntxiv