A.機(jī)械縫隙 B.離心原理 C.紙質(zhì)微孔 D.機(jī)械縫隙和紙質(zhì)微孔
A.10/~2% B.50%~80% C.5%~8% D.100%
A.200hB.250hC.500hD.600h