Hauv kev tsim kho, kho dua tshiab, thiab rhuav tshem cov haujlwm. txiav, sib tsoo, drilling txheej txheem yuav koom nrog pob zeb. Cov pob zeb yog tsim los ntawm cov cement, xuab zeb, pob zeb, thiab dej, thiab thaum cov khoom siv no raug tswj los yog cuam tshuam, cov khoom me me tuaj yeem ua rau huab cua, tsim ...
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