Before a tank is to be crude oil washed，the oxygen content in the tank must be measured at a position（）.

单项选择题Backfire flame arrestors are installed on（）.

A.fuel tanks
B.spark plugs
C.carburetors
D.distributors

单项选择题Automatic fire dampers in ventilation systems are operated by use of（）.

A.remotely operated valves
B.fusible links
C.C0₂ system pressure switches
D.heat or smoke detectors

单项选择题Automatic fire dampers in ventilation systems are operated by a（）.

A.remote operated valve
B.fusible link
C.CO₂ system pressure switch
D.heat or smoke detector

单项选择题According to the T-Boat regulations the reason for providing adequate ventilation for a battery storage area is to prevent（）.

A.accumulation of carbon dioxide gas that chokes the battery
B.accumulation of explosive and toxic gases the battery can generate
C.mildew or dry rot in the battery box
D.battery failure including battery case meltdown caused by excessive heat

单项选择题A fire starting by spontaneous combustion can be expected in which condition?（）.

A.Paints，varnish，or other liquid flammables are stowed in a dry stores locker
B.Inert cargoes such as pig iron are loaded in a wet condition
C.Oily rags are stowed in a metal pail
D.Clean mattresses are stored in contact with an electric light bulb