单项选择题
Recharging a previously used cartridge-operated dry-chemical extinguisher is accomplished by（）.
A.authorized fire equipment servicing personnel only B.replacing the propellent cartridge and refilling with powder C.puncturing the cartridge seal after installation D.recharging the cartridge and refilling it with powder
单项选择题 Radiation spreads a fire by（）.
单项选择题 Prior to getting underway，the Master or person in charge of a ship must（）.
单项选择题 Portable foam type fire extinguishers are most effective on（）.
