A.低碳鋼 B.高碳鋼 C.工具鋼
A.提高 B.保持不變 C.降低
A.H=D/2[1-cos(δ+γ)]+hcosδ B.H=D/2[1-sin(δ+γ)]+hsinδ C.H=D/2[1+cos(δ+γ)]-hcosδ