单项选择题
A.P、Fe B.Fe、C C.CO、H2 D.C、P
A.0.1~0.2% B.0.2~1.7% C.1.7~2.0% D.2.0~4%
A.10℃ B.20℃ C.50℃ D.100℃
A.1200℃ B.1300℃ C.1400℃ D.1500℃
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