单项选择题
A.Class "A"
B.Class "B"
C.Class "C"
D.Class "D"
单项选择题 A fire may be spread by which of the following means?（）
单项选择题 If emergency welding repairs must be made to the upper area of a fuel tank, the tank and/or adjacent compartments may need to be （）
单项选择题 Which of the following statements is least likely to cause the ignition of fuel vapors?（）