單項選擇題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


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1.單項選擇題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

2.單項選擇題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