单项选择题
A.improve fuel economy
B.increase the air charge velocity
C.reduce the risk of explosion
D.all of the above
单项选择题 Which of the following conditions could cause the feed pump for an auxiliary boiler to lose suction?（）
单项选择题 In readying an auxiliary water-tube boiler for a routine hydrostatic test, which of the following procedures should be undertaken prior to filling the boiler with fresh water?（）
单项选择题 The fuel supply system to an automatic auxiliary boiler, will be automatically shutdown if the boiler （）