單項選擇題After a fire has been extinguished in a closed space, personnel may safely enter the space when （）.

A.smoke density has been decreased sufficiently to see the bulkhead opposite the compartments entrance
B.a lifeline and explosion proof flash light are used
C.all smoke and toxic fumes are removed and an adequate oxygen supply is present
D.overhaul has been completed to remove any possible source of re-ignition


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1.單項選擇題Which of the petroleum products listed has the lowest flash point?（）

A.Hydraulic oil
B.Lubricating oil
C.Diesel oil
D.Refrigeration oil

2.單項選擇題Which of the listed fire extinguishers is recommended for use on an electrical switchboard fire?（）

A.CO2
B.ABC dry chemical
C.CO2 propelled foam
D.All of the above

4.單項選擇題Which of the following represents the emergency signal for fire aboard ship?（）

A.More than six short blasts and one long blast on the whistle
B.Continuous blast of the ships whistle for a period of not less than 10 seconds supplemented by the same signal on the general alarm
C.Three short blasts of the whistle supplemented by the same signal on the general alarm
D.More than six short blasts and one long blast on the whistle supplemented by the same signal on the general alarm

5.單項選擇題To extinguish an electrical fire, you should use （）.

A.mechanical foam
B.chemical foam
C.carbon dioxide
D.soda acid