propeller hub
lignum vitae
shaft packing
labyrinth seal
第1题：
Which of the following conditions could contribute to the cracking of a diesel engine cylinder head?
A.Leaking seal ring
B.Insufficient heat transfer from the exhaust valves
C.Blocked cooling water passages to the head
D.Excessive scavenging air provided to the engine
第2题：
The tourist is prevented from entering a country if he does not have ________ passport.
[A] an operative
[B] a valid
[C] an efficient
[D] an effective
第3题：
We drop a piece of metal into a jar full of water, the metal will float if it weighs less than______.
A. an equal amount of silver
B. an equal amount of gold
C. all the water in the jar now
D. the water that leaves the jar
50．答案为D 此题为推断题。根据阿基米德定理，推断试验的结果，答案选D。
第4题：
What prevents water running along the shaft of a leaking centrifugal pump from entering the shaft bearing ________．
A.Shaft seal
B.Water flinger
C.Drain hole
D.Lantern ring
第5题：
Which statement about damage control is TRUE ________．
A.A hole in the hull at the waterline is more dangerous than a hole below the inner bottom
B.The amount of water entering a ship through a hole varies inversely to the area of the hole
C.Water flowing into a lower compartment on a ship is more dangerous than water on deck or flowing into an upper compartment
D.Water flowing over the forecastle bulwark is more dangerous than a hole in the hull at the waterline
第6题：
Which of the following problems could cause the high pressure cutout switch to shut down the compressor in a refrigeration system?
A.A shortage of liquid refrigerant.
B.Excessive frost on the evaporator.
C.Excessive condenser cooling water.
D.Insufficient condenser cooling water flow.
第7题：
When the steering gear is in operation, you should ______.
A.check hydraulic oil levels every hour
B.check the rams for overheating
C.check for excessive oil leakage from rams
D.drain water from tele-motor cylinders each watch
第8题：
The main propulsion diesel engine jacket water temperature rises above normal, with the raw sea suction and the expansion tank water level being normal. Which of the following problems is most likely the cause?
A.Faulty thermostatic bypass valve
B.Eroded zinc pencils in the heat exchanger
C.Steam formation in the expansion tank
D.Excessive leakage from jacket water pump seals
第9题：
What is the major function of the deck water seal in an inert gas system ________．
A.Relieve excessive overpressures in the system
B.Isolate hazardous from nonhazardous areas
C.Prevent the flow of inert gas into closed tanks
D.Remove any leftover water or soot after the gas has been scrubbed
第10题：
CIt is desirable to have screens on the vents of potable water tanks to ______．
A.Filter the incoming air
B.Prevent explosions
C.Prevent backups
D.Stop insects from entering