单项选择题
A.9001和9000, B.9001,9000,9004 C.9001,19011, D.9000,9001,9004,9011
A.2.06% B.3.8% C.4.32% D.1.2%
A.渗碳体B.奥氏体C.莱氏体D.马氏体