碱性电弧炉炼钢中，沉淀脱氧、扩散脱氧的方法及优缺点？
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用碱性电弧炉氧化法炼钢，为什么配料时炉料的碳量要比规定的碳量高0.3～0.4%？
Advantages of zinc polycarboxylate cement include which of the following()
A. kindness to the pulp
B. 10ng working time
C. chemical adhesion to tooth structure
D. All of the above
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