單項(xiàng)選擇題

The bypass valve on a self-contained breathing device should be opened if（）.

A.you are entering a space containing poisonous vapors
B.you are entering a space containing explosive gases
C.the regulator of the breathing apparatus malfunctions
D.the face piece of the breathing device is too tight

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單項(xiàng)選擇題

The boat is stowed on the davit rather than on a cradle with which type of davit?（）

A.Crescent
B.Sheath-screw boom
C.Quadrantal
D.Radial

單項(xiàng)選擇題

Static electricity may be built up by the（）.

A.flow of petroleum through pipes
B.spraying or splashing of petroleum
C.settling of solids or water in petroleum
D.All of the above