单项选择题
A branch line valve of a fire extinguishing system on a ship must be marked with the（）.
A.maximum pressure allowed at that branch B.name of the space or spaces which it serves C.date of the last maintenance inspection D.pressure needed to maintain an effective stream at that point
单项选择题 （），as the chemical extinguisher agent，should be used for an electric fire.
单项选择题 The danger of a charged hose left unattended on deck with the nozzle open is（）.
单项选择题 No outlet on a fire hydrant may point above the horizontal in order to（）.
