Lub raj mis iav muaj qhov zoo ntawm cov txheej txheem tsim khoom yooj yim, dawb thiab hloov tau zoo, siab hardness, kub tsis kam, huv si, yooj yim tu, thiab tuaj yeem siv ntau zaus. Ua ntej tshaj plaws, nws yog ib qho tsim nyog los tsim thiab tsim cov pwm. Cov khoom siv raw ntawm lub khob iav yog quartz ...
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