单项选择题
Injectors for use with heavy fuel oil must be cooled by either water or light oil to （）
A.prevent heat corrosion to internal components B.increase fuel delivery rate and economy C.prevent pre-ignition D.avoid carbonization of the nozzle tips
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 To minimize the formation of carbon deposits on fuel injection nozzles, you should （）
单项选择题 In a simple mechanical governor, the （）
