A.20% B.2.0% C.0.20% D.0.020%
A.普通鋼 B.優(yōu)質(zhì)鋼 C.高級優(yōu)質(zhì)鋼 D.特級優(yōu)質(zhì)鋼
A.鋼板 B.汽車鋼板 C.工具 D.鋼筋