Scuffed cylinder liner wearing surfaces in a diesel engines can result from （）

A.space limitations prevent separately run pipes
B.the engines are small auxiliary units
C.they are arranged to prevent gas backflow to each engine
D.a waste heat boiler is installed

A.worn connecting rod bearings
B.worn engine cylinder liners
C.high cylinder firing pressure
D.stuck spring-loaded manhole covers

A.chromium plating piston rings
B.knurling the piston skirt
C.extended maximum power operation
D.applying load to a cold diesel engine