单项选择题
A.Q235 B.40CrMnMo C.Q460 D.20
A.CrWMn B.20 C.60Si2Mn D.T8
A.20CrMnTi B.45 C.08 D.GCr15
A.10Cr17 B.12Cr18Ni9 C.68Cr17 D.GCr15
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