单项选择题
A.1000±50 B.700±50 C.1200±50 D.900-1000
A.Fe≤±0.05%，S≤±0.01% B.S≤±0.01%，P≤±0.01% C.SiO2≤±0.4%，CaO≤±0.2% D.Fe≤±0.05%，SiO2≤±0.03%