1.Ithonya lezinto ezibonakalayo: Ibhola lensimbi, i-cast iron ball, i-alloy steel ball, njll. Ukuminyana kwezinto ezihlukene kuhlukile, ukuminyana kwensimbi kukhulu kunokwensimbi ecijile, futhi ukuminyana nokuqukethwe kwensimbi ye-alloy kuyahlukahluka kuye ngokuthi ukuminyana kanye nokuqukethwe okuyinhloko ...
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