单项选择题
Which of the listed fire extinguishers is recommended for use on an electrical switchboard fire?（）
A.CO2 B.ABC dry chemical C.CO2 propelled foam D.All of the above
单项选择题 Which of the fire extinguishing agents listed is the safest to use when combating a class C fire?（）
单项选择题 Which of the following represents the emergency signal for fire aboard ship?（）
单项选择题 To extinguish an electrical fire, you should use （）.
