1. Cov ntaub ntawv nyoos: Tag nrho cov khoom siv ua tau cov tshuaj txhuas ntshiab 99.997%, peb yuav qhia koj cov ntsiab lus hauv peb lub Hoobkas lub tsev rau khoom. Qhov no tseem ceeb heev, vim tias muaj ntau yam khoom siv ua dua qub, lub impigity alloys sab hauv yuav ua rau lub roj teeb tsis ruaj khov tsis ruaj khov. Tshwj xeeb tshaj yog cov arsenic el ...