单项选择题
A.steam rather than gas is used to turn a shaft
B.vapor rather than gas is used to turn a shaft
C.the former uses gas to turn a shaft
D.the latter uses gas to turn a shaft
单项选择题 The reason why more and more of the large merchant vessels are being powered by medium-speed diesel engines is （）.
单项选择题 The diesel engine is similar to the gasoline engine in that （）.
单项选择题 Most troubles likely to occur with marine diesel engine can, if located in time, be remedied with no difficulty and many can be （）if the engine is maintained with a high sense of responsibility to the people on the part of the motormen and engineers.