A.Automatic sprinkler systemB.Steam smothering systemC.……

单项选择题What is an advantage of using foam in fire fighting?（）

A.It is effective in controlling fire in flowing oil such as coming from a broken fuel line
B.It absorbs heat from materials that could cause reignition
C.Most foams can be used jointly with dry chemical extinguishing agents to attack a fire by two methods of extinguishment
D.Once the surface is blanketed with foam and the fire is extinguished，no further foam is required

单项选择题What is an advantage of using foam in fire fighting?（）

A.It is MOST effective on very hot oil fires where the temperatures of the liquid exceed 100°C (212°F)
B.Most foams can be used with dry chemicals to attack a fire by two methods
C.Foam is effective on combustible metal fires
D.Foam can be made with seawater or fresh water

单项选择题What does the term head mean when applied to a fire pump?（）

A.Length of the discharge pipe
B.Height of the discharge pipe
C.Difference between the discharge and suction pressures
D.Sum of discharge and suction pressures

单项选择题What does blowing tubes accomplish?（）

A.Eliminates unburned fuel oil residues from the firebox
B.Increases boiler efficiency
C.Flushes away mineral deposits inside the water tubes
D.Cleans soot deposits from the inside of the stack

单项选择题What are the most important reasons for using water fog to fight fires?（）

A.Smothers burning surfaces，organically destroys fuel
B.Cools fire and adjacent surfaces，provides protective barrier
C.Reaches areas not protected by steam or CO₂ smothering systems
D.Allows fire to be attacked from leeward，saturates liquid surfaces