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單項(xiàng)選擇題

A fire of escaping liquefied flammable gas is best extinguished by（）.

A.cooling the gas below the ignition point
B.cutting off the supply of oxygen
C.stopping the flow of gas
D.interrupting the chain reaction

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單項(xiàng)選擇題

A chemical additive to LPG gives it a characteristic（）.

A.odor
B.color
C.pressure
D.density

單項(xiàng)選擇題

On a hydrocarbon flammability chart the line which extends from 0% to 21.8% oxygen，lying tangent to the flammability range，is called the（）.

A.mimimum oxygen content line
B.critical displacement line
C.critical dilution line
D.upper threshold limit

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