单项选择题
A.0.70~1.00% B.1.00~1.20% C.1.20~1.70% D.1.70~2.00%
A.0.045% B.0.035% C.0.030% D.0.020%
A.普通钢 B.优质钢 C.高级优质钢 D.特级优质钢