A.普通鋼 B.45號優(yōu)質(zhì)碳素鋼 C.60號優(yōu)質(zhì)碳素鋼
A.33.44mJ(8000千卡) B.29.26mJ(7000千卡) C.25.08mJ(6000千卡)
A.閉路 B.開路 C.預篩開路