（）sometimes called filter, is a device designed to prevent the passage of unwanted solids into the system.

A.lobe type
B.screw type
C.axial piston type
D.volute type

A.increase the fuel oil temperature
B.decrease the fuel oil temperature
C.decrease the fuel oil supply pressure
D.increase the air supply

A.keyway
B.shaft
C.packing
D.valve