单项选择题
When the boiler load returns to normal, the drum pressure will rise and steam bubble formation will reduce, causing a fall in water level This is known as （）.
A.swell B.shrinkage C.flash off D.lack of water
单项选择题 WHR stands for （）.
单项选择题 As for a oil-fired boiler too much air would indicated by （）.
单项选择题 As for an oil-fired boiler if at a normal steaming condition and water goes out of sight in gauge glasses the action you should take is: （） (1) secure oil to fires (2) increase feed pump pressure
