Except in rare cases，it is impossible to extinguish a shipboard fire by（）.

A.it is impractical to locate them outside
B.there is also a control valve outside
C.the CO₂ cylinders are also in the space
D.an automatic heat-sensing trip is installed

A.NOT contain more than 200 pounds of CO₂
B.be automatically operated by a heat actuator
C.have an audible alarm
D.All of the above

A.the discharge valve is open
B.the control box glass is broken
C.pressure from the control cylinders is detected
D.the control cylinders have been completely discharged