单项选择题
The three basic elements necessary for any fire are （）.
A.heat, gas, and flames B.fuel, heat, and oxygen C.heat, nitrogen, and fuel D.fuel oil, nitrogen, and oxygen
单项选择题 Engines for lifeboats are required to have sufficient fuel to operate for how many hours?（）
单项选择题 If a fire occurs in the boiler room as a result of a leaking fuel line, you should FIRST （）.
单项选择题 The four basic components of a fire are chain reaction, heat, fuel, and （）.
