单项选择题
A.≤0.035% B.≤0.03~0.02% C.≤0.03% D.≤0.0035%
A.热脆 B.冷脆 C.白点 D.时效性
A.≥0.045% B.≤0.045% C.≥0.0045% D.≤0.0045%