题目内容

The ( )engine usually be directly coupled to the propeller as the maximum efficiency of each can be matched at a suitable rotational speed.

A. slow speed two-stroke
B.medium speed four-stroke.
C. medium speed two-stroke
D.high speed four-stroke

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The influence of frictional and residual resistances depends on how much of the hull is( )the waterline,while the influence of air resistance depends on how much of the ship is( )the waterline.

A. below;above
B. below; below
C. above; below
D. above;above

( )allows the engines to be placed wherever is the most suitable, as they no longer have to be aligned with reduction gearing and shafting as is the case with conventional installations.

A. Diesel engine propulsion
B. Electrical propulsion
C. Steam engine propulsion
D. Gas turbine propulsion

Of all types of commercial internal combustion engines now built, which one usually gives the best performance,and hence it is quite commonly used in marine applications,especially in larger sizes?( )

A. Steam engine.
B. Gasoline engine.
C. Gas turbine.
Diesel engine.

What is the application of high-speed diesel engines at sea?( )①They are used for emergency power generation to small applications; ②They are used forelectrical power generation on board ships driven by medium-speed propulsion engines;③They can be used on tugs,ferries and barges, etc. as main engines.

A. ①②.
B. ②③.
C. ③.
D. ①②③.