【名词&注释】
使用寿命(service life)、液压油(hydraulic oil)、制冷剂(refrigerant)、齿轮箱(gearbox)、制冷量(cooling capacity)、轴功率(shaft power)、固定式(fixed)、自变量(independent variable)、不一定(not always)、差不多(near)
[单选题]The water in an auxiliary boiler should be tested for chloride content to determine ( ).
A. total dissolved solids
B. salt contamination
C. water harcness
D. chlorine contamination