Ua ntej tshaj plaws, qhov saum npoo ntawm lub raj tooj dag siab yuav tsim cov txheej txheem tiv thaiv nyuaj, txawm tias nws yog roj, carbohydrates, cov kab mob thiab cov kab mob, cov dej tsis zoo, oxygen lossis ultraviolet rays, nws tsis tuaj yeem dhau los ntawm nws, thiab tsis tuaj yeem ua tau. yuav eroded rau pollute dej zoo, thiab parasites yuav ...
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