What is the function of an air receiver in the compressed air system on a ship? （）

单项选择题What is the female section of a tool joint called? （）

A.Stem
B.Pin
C.Box
D.Stand

单项选择题What is the best instrument for establishing a safe working area before welding in a confined space? （）

A.An oxygen indicator
B.A combustible gas indicator
C.A combination combustible gas and oxygen indicator
D.A flame safety lamp

单项选择题What is the BEST conductor of electricity?（）

A.Carbon dioxide
B.Distilled water
C.Fresh water
D.Salt water

单项选择题Upon completion of fueling a gasoline driven vessel it is necessary to（）.

A.keep ports，doors，windows，and hatches closed
B.start engines immediately
C.ventilate before starting engine
D.None of the above

单项选择题There are（）rats on board.

A.not
B.no
C.any
D.none