Kev lag luam tshuaj lom neeg thoob ntiaj teb
Kev lag luam tshuaj lom neeg thoob ntiaj teb yog qhov nyuaj thiab tseem ceeb ntawm kev lag luam thoob ntiaj teb thiab cov khoom siv sib txuas. Kev tsim cov tshuaj muaj xws li hloov cov ntaub ntawv raw xws li fossil fuels, dej, minerals, hlau, thiab lwm yam, mus rau ntau txhiab tus diff...
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