单项选择题
A.is coming upward；cylinder ring belt B.is going downward；piston ring belt C.is coming upward；piston ring belt D.is going downward；cylinder ring belt
（）diesel engines generally have two systems of lubricat...
单项选择题（）diesel engines generally have two systems of lubrication:（）a total loss system feeding and a circulating system lubricating the running gear and cooling the pistons.
A.Large crosshead type；crossheads B.High speed；the cylinders C.Large crosshead type；the cylinders D.Four-stroke；pistons and cylinders
The following options are all the functions of lubricat...
单项选择题The following options are all the functions of lubricating oil except（）
A.removing heat and deposits B.neutralizing acidic products C.lubricating D.improving combustion efficiency
The air distributor is conventionally driven by（） and d...
单项选择题The air distributor is conventionally driven by（） and distributes into each cylinder by（） certain sequence.
A.camshaft；fresh air B.camshaft；starting air C.electronic motor which is controlled by a computer；fresh air D.electronic motor which is controlled by a computer；starting air
