Qhov cuam tshuam ntawm ntim cov ntaub ntawv ntawm ib puag ncig thiab cov khoom siv Cov ntaub ntawv yog lub hauv paus thiab lub hauv paus ntawm kev txhim kho kev lag luam hauv lub tebchaws thiab kev sib raug zoo. Nyob rau hauv cov txheej txheem ntawm cov khoom sau, extraction, npaj, ntau lawm, ua, thauj, siv thiab pov tseg, ntawm ib sab, nws ...
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