Cov tswv yim lim ua haujlwm li cas

Cov lus qhia lim muaj cov khoom lim sab hauv uas tshem tawm cov impurities thiab cov khoom ntawm cov kua. Thaum lub sij hawm aspiration, lub ntsiab lim lim cov kua, kom ntseeg tau tias nws yog ntshiab thiab tsis muaj impurities. Cov yam ntxwv no ua rau cov lus qhia lim tshwj xeeb muaj txiaj ntsig hauv kev sim microbiology.