单项选择题
Propeller running at （） are generally efficient.
A.high speeds
B.medium speed
C.low speeds
D.the same speed with the engine
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相关考题
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单项选择题
Which is not the maintenance work for shaft bearings in transmission system?（）
A.check oil level in bearing sump
B.check them for leakagec through end seals
C.pump bilges in time
D.check temperature -
单项选择题
Water lubricated tailshaft bearings wear,（）
A.the after one is more than forward one
B.the forward one is more than after one
C.the forward one is the same with after one
D.it depends on the type of engine -
单项选择题
When sailing in cold zones, the（） should be drained of water.
A.the ventilation pipe
B.the water line for fire fighting on the deck
C.the fuel oil line
D.the water supplying line in bath room
