Each ship having an inert gas system must have a portable instruments to measure concentrations of hydrocarbon vapor in inert atmospheres and also to measure ______.
A.nitrogen
B.oxygen
C.carbon dioxide
D.water vapor
正确答案：B
每一艘具有惰性气体系统的船舶必须有一个用于测量惰化空气中碳氢化合物气体和氧气浓度的便携式设备
