1.Material influence: steel pob, cam khwb cia hlau pob, alloy steel pob, thiab lwm yam. Qhov ceev ntawm cov ntaub ntawv sib txawv yog txawv, qhov ntom ntawm cov hlau yog ntau dua li cov hlau cam khwb cia, thiab qhov ceev thiab cov ntsiab lus ntawm alloy steel sib txawv raws li cov khoom siv. ceev thiab cov ntsiab lus ntawm lub ntsiab ...
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