单项选择题
Control of flooding should be addressed（）.
A.first B.following control of fire C.following restoration of vital services D.only if a threat exists
单项选择题 Control of fire on a ship should be addressed（）.
单项选择题 Combustible gas indicators measure the presence of combustible gas as a percentage of the（）.
单项选择题 CO2 extinguishes a fire by（）.
