单项选择题
The FIRST course of action in fighting a fire in a cargo or fuel oil tank is to （）.
A.secure all openings to the tank B.discharge an initial charge of CO2 with a hand portable extinguisher C.direct a fire hose into the tank and energize the fire main D.spray the tank boundaries with a fire hose to promote cooling
单项选择题 In fighting a fire in a fuel tank, the FIRST action you should attempt is to （）.
单项选择题 Which of the following conditions is true concerning a flammable liquid with a concentration above the upper explosive limit?（）
单项选择题 The volatility of a liquid is the tendency of a liquid to （）.
