单项选择题
A.bridges B.recesses C.rears D.ridging
Each cylinder liner on the marine medium speed engines ...
单项选择题Each cylinder liner on the marine medium speed engines （）.
A.is usually cooled by sea water B.can be replaced when worn out C.is in direct contact with the water in the bore of the cylinder D.can t expand when heated
Each cylinder is closed at the top by a （）, made of a s...
单项选择题Each cylinder is closed at the top by a （）, made of a special heat-resistant steel.
A.cylinder liner B.coupling flange C.cylinder cover D.piston crown
Each cylinder has one starting valve which is usually o...
单项选择题Each cylinder has one starting valve which is usually opened by air pressure and closed by （）
A.nuts and bolts B.new joints C.spring force D.sealing rings
