單項(xiàng)選擇題

Diesel fuel vapors （）.

A.can not be ignited by a spark unless the vapor is in a confined space
B.are nontoxic in all concentrations
C.can not be ignited by a spark unless they are at their auto-ignition temperature
D.are heavier than air

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單項(xiàng)選擇題

All of the following are part of the fire triangle EXCEPT （）.

A.fuel
B.oxygen
C.heat
D.electricity

單項(xiàng)選擇題

The vapors given off by heated fuel oil are heavier than air and are（）.

A.odorless
B.explosive
C.nontoxic
D.visible