Pob valve yog cov khoom siv tswj dej ntau, yog siv dav hauv roj av, tshuaj lom neeg, kev kho dej, zaub mov thiab lwm yam lag luam. Daim ntawv no yuav qhia txog cov qauv, kev ua haujlwm, kev faib tawm thiab kev siv cov xwm txheej ntawm lub pob valve, nrog rau cov txheej txheem tsim khoom thiab cov khoom siv ...
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