单项选择题
Each inert gas system must be designed to supply the cargo tanks with a gas，or mixture of gasses，that has an oxygen content by volume of（）.
A.5% or less B.10% or less C.15% or less D.20% or less
单项选择题 Compared to the amount of concentrated foam liquid used，the amount of low expansion mechanical foam produced is（）.
单项选择题 Combustible gas indicators operate by drawing an air sample into the instrument（）.
单项选择题 Butadiene，inhibited，is labeled as a（）.
