A.0-20r/min B.15-25r/min C.20-35r/min
A.把煤粉從氣粉混合物中分離出來 B.把粗粉和細(xì)粉分離出來 C.把雜質(zhì)和細(xì)粉分離出來
A.5% B.15% C.25% D.35%