单项选择题
A.more water contents B.contamination with fuel oil C.higher temperature D.sufficient cooling of oil mist
The mechanical efficiency of an engine （） because losse...
单项选择题The mechanical efficiency of an engine （） because losses occur in the form of friction.
A.is always less than 100% B.is always more than 100% C.is always equal to 90% D.is always less than 90%
The marine diesel engine is a type of diesel engine use...
单项选择题The marine diesel engine is a type of diesel engine used on ships The （） of its operation is not very difficult to understand.
A.principle B.principal C.cause D.case
The majority of medium speed and high speed marine dies...
单项选择题The majority of medium speed and high speed marine diesel engines for main or auxiliary drive operate on the （） cycle.
A.two-stroke B.four-stoke C.long-stroke D.short-stroke
