单项选择题
The efficiency and output capacity of a low pressure distilling plant will be reduced if the last effect shell （）
A.pressure does not fluctuate rapidly
B.pressure remains steady and unchanged
C.brine density does not exceed 1~5
D.brine density is too low
相关考题
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单项选择题
In most pumps and pump motors overpacking the ball bearings full of grease will result in （）
A.moisture emulsification of the bearing grease
B.insufficient circulation and overheating of the bearing
C.proper grease circulation to cool the bearing
D.sliding friction between balls and races -
单项选择题
Aqueous Film Forming Foam (AFFF), commonly known as ‘light water’, is especially suitable for fighting （）
A.oil fires in the engine room bilges
B.class B fires in paint lockers
C.any class D fire
D.all of the above -
单项选择题
Which of the following statements concerning the water tube and fire tube boilers is not true?（）
A.natural circulation of the water in the water tube boiler is better than that in the fire tube boiler
B.for the same output the water tube boiler will carry less mass of water compared with the fire tube boiler
C.the water tube boiler will cost shorter time for steam raising
D.the water tube boiler require lower skill in operating and maintaining
