单项选择题
The plunger in the fuel injector pump, usually operated by a （）, is driven up and down when working.
A.crankshaft B.camshaft C.piston rod D.rack and pinion
单项选择题 The pistons are cooled by oil supplied from the forced （） system.
单项选择题 The piston supporting body is mainly subjected to （） stress.
单项选择题 The piston rings if found worn out （） and supplied by shipchandler.
