Lub nplhaib iav feem ntau yog tsim los ntawm cov txheej txheem uas muaj ob peb kauj ruam tseem ceeb, suav nrog forging lossis casting, machining, hea kho, thiab ua tiav. Ntawm no yog ib qho kev nthuav dav ntawm cov txheej txheem tsim khoom siv rau lub nplhaib iav: Kev Xaiv Khoom: Cov txheej txheem pib nrog kev xaiv ...
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