单项选择题
A.above B.at C.over D.within
Before replacing a piston you should check that all rin...
单项选择题Before replacing a piston you should check that all rings are （）.
A.free B.fastened C.broken D.stuck
Before pumping up the crankcase oil,（） should be worked...
单项选择题Before pumping up the crankcase oil,（） should be worked by hand to minimize corrosive action on the liners.
A.the indicators B.the starting valves C.the cylinder lubricators D.the turning gear
Before being used the fuel service tank should be drain...
单项选择题Before being used the fuel service tank should be drained of （）.
A.soda solution B.mechanical impurities C.ballast D.water and residuals
