单项选择题
After using a Halon extinguisher，it should be（）.
A.put back in service if more than 50% of the charge remains B.repainted C.discarded D.recharged
单项选择题 After using a C02 portable extinguisher，it should be（）.
单项选择题 Accumulations of oily rags should be（）.
单项选择题 A high-velocity fog stream can be used in fire fighting situations to drive heat and smoke ahead of the fire fighters in a passageway. This technique should only be used when（）.
