单项选择题
A.Mn B.Si C.P D.S
A.Mn B.H C.P D.N
A.C%<0.7% B.C%<0.9% C.C%<1.4% D.C%<0.8%
A.C%=0.7% B.C%=0.9% C.C%=0.4% D.C%=1.3%
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