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 （）.
A.loss of suction in the circulating pump B.leak in the primary cooling system C.broken raw water pump shaft D.burned or cracked piston in one cylinder
单项选择题 In a simple mechanical governor, the （）.
单项选择题 The ability of the governor to prevent fluctuations in engine speed is termed （）.
单项选择题 What is the function of the thrust bearing?（）
