Tam sim no, cov khoom tseem ceeb ntawm cov ntsia hlau kab ntau lawm yog: ntawv sawb ntsia thawv, yas sawb ntsia thawv, hlau ntsia hlau kab, thiab lwm yam., cov duab ntawm ib tug ntsia thawv yog muab faib ua F, T, U thiab hais txog. Raws li nws cov txheej txheem ntau lawm, kab cov ntsia hlau tuaj yeem muab faib ua ob pawg ...
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