单项选择题
In fighting a fire in a fuel tank, the FIRST action you should attempt is to （）.
A.secure all sources of fresh air to the tank B.begin transferring the fuel to other tanks C.top off the tank to force out all vapors D.station someone at the fixed CO2 release controls
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 （）.
单项选择题 An oxygen indicator will detect （）.
