One end of a diesel engine cylinder is sealed by the cylinder head and the other end by the （）

A.discharge exhaust gases and smoke
B.furnish energy to the turbocharger
C.reduce engine room noise
D.all of the above

A.residual carbon deposits
B.lube oil viscosity breakdown
C.uneven heat expansion of the rings
D.uneven heat expansion of the piston

A.one-half engine speed
B.the same as engine speed
C.twice engine speed
D.four times engine speed