单项选择题
A.0.5%～1% B.1%～2% C.1%～3% D.2%～3%
A.1% B.2% C.3% D.4%
A.5% B.10% C.15% D.25%
A.合金钢 B.低碳钢 C.中碳钢 D.高碳钢
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