单项选择题
A.because B.thanks to C.dues to D.owing to
The mechanical efficiency of an engine is always less t...
单项选择题The mechanical efficiency of an engine is always less than 100% （） losses occurring in the form friction.
A.because B.since C.due to D.owing to
The pressure difference before and after the lube oil f...
单项选择题The pressure difference before and after the lube oil filter indicates （）the filter should be cleaned.
A.when B.how C.where D.whether
A diesel engine which is rated for normal operation at ...
单项选择题A diesel engine which is rated for normal operation at a crankshaft speed of 800 RPM, is commonly classed as a （）.
A.slow-speed diesel B.medium-speed diesel C.high-speed diesel D.constant-speed diesel
