A.45號(hào)鋼 B.30號(hào)鋼 C.15號(hào)鋼 D.40號(hào)鋼
A.35號(hào)鋼 B.45號(hào)鋼 C.65號(hào)鋼 D.40號(hào)鋼
A.0.20% B.0.45% C.0.35% D.0.65%