Vim muaj kev cuam tshuam los ntawm covid-19, tau muaj qhov tsis txaus ntawm cov khoom siv chips thoob plaws ntiaj teb, ua rau muaj kev nce nqi ntawm ntau cov khoom, ntau tus nqi nce, thiab cov khoom muag tsawg thiab tsawg. Ntau lub tuam txhab muaj cov khoom tsis txaus, xws li Siemens, Delta, Mitsubishi ...
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