单项选择题
A “fifteen-pound” CO2 extinguisher is so called because（）.
A.there are fifteen pounds of CO2 in the container B.the container，when full，weighs fifteen pounds C.the pressure at the discharge nozzle is l5 psi D.the empty container weighs fifteen pounds
单项选择题 A “check” line is（）.
单项选择题 A “bowline” is used to（）.
单项选择题 “safe speed” is defined as that speed where（）.
