lab iav siv (1) Cov raj siv tau siv ntau: me me ntawm cov tshuaj tiv thaiv cov hlab ntsha; Nws kuj tseem siv tau los ua lub thawv ntim khoom me me; los yog lub tshuab hluav taws xob rau kev txhim kho cov roj me me. (2) Beakers feem ntau yog siv rau: kom yaj cov khoom, cov tshuaj npaj thiab dilution thiab