单项选择题
A.larger than B.smaller than C.equal to D.none of the above
The piston ring grooves for a standard engine are （）A.c...
单项选择题The piston ring grooves for a standard engine are （）
A.chromium-plate against wear B.anti-corrosion treated C.white metal lined against wear D.flame hardened against wear
The piston moving up and down keeps the crankshaft （）.A...
单项选择题The piston moving up and down keeps the crankshaft （）.
A.to revolve B.revolved C.revolving D.to be revolved
The piston moves up and down, thus causing the rotation...
单项选择题The piston moves up and down, thus causing the rotational movement of the（）
A.crankshaft B.connecting rod C.cross-head D.main beating
