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
单项选择题 The following options are all the functions of lubricating oil except（）
单项选择题 The air distributor is conventionally driven by（） and distributes into each cylinder by（） certain sequence.
单项选择题 When an engine is starting and has got a sufficiently high speed, say about 20 rpm,（）
