单项选择题
A.20~40B.10~30C.30~60D.40~70
A.40~100mmB.60~110mmC.50~100mmD.70~120mm
A.棉纱B.少量黄沙C.混煤粉D.以上都有
A.20t/hB.25t/hC.30t/hD.35t/h
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