单项选择题
A.they operate between 150 and 450 rpm
B.they are connected to the propeller by gearing
C.their smaller size and weight
D.they can be connected directly to the propeller without gearing
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.
单项选择题 If （） are taken at regular intervals, any unequal distribution of load will be easily found out.