单项选择题
A.the cylinder cover
B.the piston rings
C.the piston crown
D.the piston skirt
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.
单项选择题 Modem engines （） exhaust gas driven turbo-chargers to supply pressurized fresh air for scavenging and supercharging.