单项选择题
A.lower than；can lubricate
B.lower than；can cool
C.higher than；can enter
D.higher than ；cannot enter
单项选择题 Oil is supplied to the cylinder wall and （） by means of mechanical lubricators.
单项选择题 No specific period is given for the renewal of the lubricating oil filter element as this should be done（） a figure of 0√7 bars is shown on the gauge.
单项选择题 Modem engines make use of exhaust gas driven turbo-chargers to supply pressurized fresh air for （） and supercharging.