单项选择题
The function of diesel engine piston compression rings is to （）.
A.prevent piston side thrust B.prevent engine friction losses C.transmit heat from the piston to the cylinder liner D.remove oil from the cylinder combustion space
单项选择题 A diesel engine piston ring face is in direct contact with the （）.
单项选择题 If the water level dropped rapidly in the expansion tank of a closed diesel engine cooling water system, you should suspect a （）.
单项选择题 In a simple mechanical governor, the （）.
