A.提高排氣壓力,使Hn減小 B.提高排氣壓力,使Hn增大 C.降低排氣壓力,使Hn減小 D.降低排氣壓力,使Hn增大
A.45° B.9O° C.75° D.180°
A.0.2~0.4mm B.0.4~0.6mm C.0.6~0.8mm D.小于0.2mm