单项选择题
A.both of them are ignited by compressed air
B.both of them are the forms of external combustion engines
C.both of them have spark plugs
D.the power is developed by the piston in the cylinder
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.
单项选择题 If the action of the engine indicates that some of the cylinders are not firing, the ones affected may be determined by watching （）.