单项选择题

The crankcases of many diesel engines are kept under a slight vacuum to （）

A.improve fuel economy
B.increase the air charge velocity
C.reduce the risk of explosion
D.all of the above

相关考题

Which of the following conditions could cause the feed ...

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A.Increased suction head pressure
B.Decreased feedwater temperature
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D.Excessive feedwater temperature

In readying an auxiliary water-tube boiler for a routin...

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A.The safety valve escape piping should be disconnected from the valve body and a blank inserted
B.The boiler vent valves should be opened
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D.All of the above

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单项选择题The fuel supply system to an automatic auxiliary boiler, will be automatically shutdown if the boiler （）

A.salinity is abnormally high
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D.feedwater flow is low

船舶动力装置

The crankcases of many diesel engines are kept under a slight vacuum to （）