单项选择题 There is a （） system lubricating the running gear and cooling the piston and sometimes lubricating the cylinders.

单项选择题 There is （） in any water cooling system for a diesel engine allowing for expansion and water make-up in the system as well as air vent and chemicals addition.

单项选择题 The working cycle of a four-stroke diesel engine consists of four events:（） (1) compression (2) expansion (3) exhaust (4) suctionThe correct sequence is