单项选择题
A.＜0.03% B.＜0.08% C.≦0.0218% D.≦0.25%
A.＜0.08% B.＜0.0218% C.≦0.25% D.≦0.02%
A.5% B.10% C.12% D.15%
A.Ti B.Cr C.Mo D.Ni
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