Ib zaug ntsia, thov tsis txhob txav los yog tshem lub iav chav dej ntawm qhov xav tau.Thaum txhim kho, nthuav bolts tuaj yeem siv tau.Thaum drilling, xyuam xim rau ntau yam ntawm cov vuas luaj ceramic.Yog hais tias nws yog tag nrho cov ceramic, siv cov dej laum me ntsis, txwv tsis pub nws yooj yim heev rau tawg.Yog tias siv iav nplaum rau ...
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