单项选择题
A.20-40 B.40-60 C.60-80 D.80-100
A.1537-(88C%+8Si%+4Mn%+30P%+25S%) B.1537-(88C%+9Si%+5Mn%+30P%+25S%) C.1537-(88C%+8Si%+5Mn%+30P%+25S%) D.1537-(88C%+8Si%+5Mn%+30P%+29S%)
A.上下偏低,而中间温高 B.上下偏高,而中间温低 C.自上而下温度递减 D.都一样
A.10-30,50-100 B.50-100,10-30 C.20-60,60-100 D.60-100,20-60
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