单项选择题
A.high steam pressure in the boiler
B.abnormally high feed water temperature
C.abnormally high boiler water temperature
D.steam demand exceeding feed pump capacity
单项选择题 Which of the following conditions can cause above normal air temperature to develop in the intake manifold of a four-stroke/cycle turbo-charged diesel engine?（）
单项选择题 Lubricating oil systems for diesel engine journal bearings are usually lubricated by which of the following types of lubricating oil systems?（）
单项选择题 The crankcase of many diesel engines are kept under a slight vacuum by the （）.