Carbon dioxide flooding system is used for extinguishing fires because it reduces the concentration of oxygen in the air to（）.

单项选择题Where shall the key to C02 room be kept?（）

A.In master's cabin
B.In third office's cabin
C.In a break-glass-type enclosure conspicuously located adjacent to the room
D.In a locked locker conspicuously located adjacent to the room

单项选择题Your vessel is crossing a narrow channel.A vessel to port is within the channel and crossing your course.She is showing a black cylinder.What is your responsibility?（）

A.hold your course and speed
B.sound the danger signal
C.begin an exchange of passing signals
D.do not cross the channel if you might impede the other vessel

单项选择题The disinfection of various compartments in a vessel by filling with a gaseous agent to destroy rats and all insects pests which act as germ carriers means（）.

A.displacement
B.fumigation
C.discharging
D.compensation

单项选择题Backing means the wind（）.

A.is changing clockwise in direction
B.is changing anticlockwise in direction
C.is changing cyclonically or variably in direction
D.remains unchanged in direction at the time

单项选择题When a feature remains in its existing charted position but has a change of characteristic,（）command is used on a chart.

A.MOVE
B.DELETE
C.AMEND
D.SUBSTITUTE