Fire extinguishers of sizes III，IV，and

1、Portable foam type fire extinguishers

Portable foam type fire extinguishers are most effective on（）.Amattress firesBoil firesCwood firesDAll of the above

2、The size of ball and roller bearings c

The size of ball and roller bearings can be identified by the （）.Arolling member sizeBinner race cone widthCmanufacturers numerical codeDouter ring width

3、Which portable fire extinguisher shoul

Which portable fire extinguisher should be used on a class C fire on board a vessel?（）ACarbon dioxideBWater (stored pressure)CFoamDCarbon tetrachloride

4、Foam extinguishes a fire by（）.

Foam extinguishes a fire by（）.Asmothering the burning materialBchemical combination with burning materialCabsorbing the burning materialDorganic destruction of the burning material

5、Halon extinguishes a fire by（）.

Halon extinguishes a fire by（）.Abreaking the chain reactionBsmothering the fireCcooling the fireDcoating the fuel with a nonflammable surface

6、Foam extinguishes a fire by（）.

Foam extinguishes a fire by（）.Ashutting off the air supplyBcooling the fuel to below ignition temperatureCdispersing the fuelDremoving the source of ignitio