单项选择题 Operating a diesel engine for prolonged periods, with a closed freshwater cooling system, at temperatures lower than the normal design temperature can cause （）.

单项选择题 Improper maintenance of the fuel oil burners in an automatically fired auxiliary boiler, could result in （）

单项选择题 Which of the following conditions may need to be reduced when operating a large, low speed, main propulsion, diesel engine at low loads?（）