单项选择题 A four-stroke/cycle, 1000horsepower diesel engine fails to start at normal cranking speed with normal fuel pressure and ambient temperatureThe reason for the failure could be（）

单项选择题 In a main propulsion turbocharged diesel engine, the speed of the turbocharger varies according to the （）

单项选择题 If you notice smoke coming fro the crankcase exhaust fan outlet of an operating diesel engine, you would suspect（）