单项选择题
A.平炉 B.转炉和大型平炉 C.电炉 D.什么炉型均可
A.S≤0.055%P≤0.055% B.S≤0.045%P≤0.045% C.S≤0.055%P≤0.045% D.S≤0.55%P≤0.45%
A.0.25~0.80 B.0.25~0.60 C.0.30~0.65 D.0.35~0.70