The propeller consists of a （）with several blades of helicoidal form attached to it.

单项选择题Oil pressure in the lubrication system is（）than the static sea water head to ensure that sea water cannot enter the sterntube in the event of seal failure.

A.higher
B.lower
C.very higher
D.very lower

单项选择题（）is used to prevent the entry of sea water to the machinery space.

A.A special sealing gland
B.Propeller
C.Tailshaft
D.Sterntube bearing

单项选择题The thrust from the propeller to the hull of the ship is transferred by（）

A.tie rod
B.thrust block
C.bedplate of main engine
D.frame of main engine

单项选择题The transmission system transmitting power from the engine to the propeller is composed of shafts, bearings, and（）

A.propeller
B.flying wheel
C.main engine
D.crankshaft

单项选择题Which of the followings will affect the spray of fuel oil?（）

A.coke deposits
B.cylinder water temperature
C.asphalt in fuel oil
D.lub oil