Diesel engine piston ring blow-by is usually caused by excessive ring clearance at the ring（）

A.crankcase pressure
B.compression pressure
C.scavenge pressure
D.exhaust manifold pressure

A.centrifuging the fuel
B.using it in the engine
C.heating the fuel tanks
D.starting the fuel

A.cooling water
B.fuel oil
C.sea water
D.diesel intake air