单项选择题
A.0.4mm B.0.3mm C.0.2mm D.0.1mm
A.45° B.55° C.60° D.75°
A.4m/s B.5m/s C.3.5m/s D.2.5m/s
A.烟煤 B.贫煤 C.无烟煤 D.标准煤
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