单项选择题
A.150~220m/minB.200~280m/minC.220~300m/min
A.低氮钢B.低磷钢C.低硫钢
A.0.01%~0.02%B.0.02%~0.03%C.0.03%~0.04%
A.8minB.13minC.15min
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