单项选择题
Before an auxiliary boiler is shutdown for an extended period of time, the water in the boiler should have a pH value of （）.
A.10
B.7
C.4
D.1
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If over a period of weeks the air-box pressure of a turbo-charged, diesel engine, operating at full load, appears to be dropping off, the cause can be （）.
A.open air-box drains
B.loss of cooling water to the diffuser
C.gradual fouling of the air filters
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单项选择题
The most common cause of scale formation in an auxiliary boiler is （）
A.concentrations of calcium sulfate in the boiler water
B.fuel oil in the feed water
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D.excessive feed water alkalinity -
单项选择题
For proper operation, auxiliary boiler feed water must have which of the following characteristics?（）
A.High oxygen concentration
B.Low pH
C.Proper alkalinity
D.All of the above
