单项选择题
A.boiler B.heater C.engine D.cooler
Cooling enables the engine metals （） their mechanical p...
单项选择题Cooling enables the engine metals （） their mechanical properties.
A.to retain B.to remain C.to maintenance D.to have
Constant cooling the various components of diesel engin...
单项选择题Constant cooling the various components of diesel engine has a number of functions except for （）.
A.good lubrication B.low thermal stress C.good mechanical properties D.acid corrosion
Compressed air is used on board ship （）.A.for starting ...
单项选择题Compressed air is used on board ship （）.
A.for starting diesel engines B.in pneumatic control system C.in pneumatic tools D.All the above are true
