单项选择题
A.An air receiver B.An operating valve C.An automatic valve D.An air distributor
（） is made of a boss with separated blades mounted into...
单项选择题（） is made of a boss with separated blades mounted into it.
A.A variable pitch propeller B.A variable pitch nut C.A fixed pitch parallel D.A fixed pitch screw
（） is fully floating in both connecting rod small end a...
单项选择题（） is fully floating in both connecting rod small end and the piston skirt.
A.The piston rod B.The cross head pin C.The gudgeon pin D.The crank-pin
（） is arranged for cleaning the lubricating oil in the ...
单项选择题（） is arranged for cleaning the lubricating oil in the system and clean oil can be provided from a storage tank.
A.A filter B.A centrifuge C.A distiller D.A generator
