单项选择题
Which is a disadvantage of Halon as a fire extinguishing medium?（）
A.Conducts electricity B.Difficult to store C.Large volume necessary to be effective D.Ineffective in powdered metal fires
单项选择题 Which firefighting method is an example of an indirect attack on a fire?（）.
单项选择题 Which fire extinguishing agent has the greatest capacity for absorbing heat?（）
单项选择题 Which fire extinguishing agent can NOT be used on an ethylenediamine?（）
