单项选择题
The water in an auxiliary boiler should be tested for chloride content to determine （）.
A.total dissolved solids B.salt contamination C.water hardness D.chlorine contamination
单项选择题 Cooling the intake air supplied to a diesel engine will （）.
单项选择题 Excessive vibration of an automatically fired auxiliary boiler can be caused by （）
单项选择题 When there is a flame failure in an automatically fired auxiliary boiler, the （）.
