单项选择题
After using a CO2 extinguisher on a ship，it should be（）.
A.put back in service if some CO2 remains B.hydrostatically tested C.retagged D.recharged
单项选择题 After each reading of an oxygen indicator，the instrument should be purged with（）.
单项选择题 Actuating the CO2 fixed system causes the shutdown of the（）.
单项选择题 A safety outlet is provided on the CO2 discharge piping to prevent（）.
