A.to protect
B.to guard
C.to maximize
D.to minimize

A.will be speeded up
B.should be slowed down
C.must slow down
D.have to be slow down

A.the trunking should be opened up
B.should the trunking be opened up
C.the trunking should not be opened up
D.should the trunking not be opened up

A.cooling jacket
B.cylinder liner
C.piston crown
D.cylinder cover

A.the camshaft
B.the flange
C.the ridge
D.the bulge

A.charge air receiver
B.scavenging air belt
C.turbine
D.air cooler

A.thrust block
B.sounding rod
C.connecting rod
D.push rod

A.a cooling system
B.a lubrication oil system
C.an electric system
D.an injection system

A.much
B.more
C.most
D.less

A.lower than；can lubricate
B.lower than；can cool
C.higher than；can enter
D.higher than ；cannot enter

A.the cylinder cover
B.the piston rings
C.the piston crown
D.the piston skirt