Failure to open the diesel engine test cocks after a long period of shutdown, prior to starting may result in （）

A.excessive fuel oil temperature
B.long periods of engine overload
C.metallic contact between nozzles and cylinder heads
D.hard carbon deposit and varnish on the nozzles

A.opposed to the crankshaft rocking couple
B.resonant with the crankshaft natural frequency
C.critical fore and aft crankshaft vibrations
D.horizontal whipping motions of the crankshaft

A.cylindrical in shape with service connections located at the top and bottom
B.opened and made available for inspection during biannual inspections provided
C.with automatic drain traps for the removal of moisture
D.so installed as to make the drain connections effective under extreme conditions of trim