单项选择题
A.复合材料风管 B.防火材料风管 C.绝热材料风管 D.防爆材料风管
A.0,0.2MPa B.0,0.1MPa C.1,0.2MPa D.1,0.1MPa
A.0.4MPa B.0.1MPa C.0.2MPa D.0.3MPa
A.5min B.50min C.10min D.20min
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