A.Factor of safetyB.Number of wires per strandC.Number ……

单项选择题A CO2 extinguisher on a ship which has lost 10% of its charge must be（）.

A.used at the earliest opportunity
B.hydro-tested
C.recharged
D.weighed again in one month

单项选择题A chart with a scale of 1:80，000 would fall into the category of a（）.

A.sailing chart
B.general chart
C.coastal chart
D.harbor chart

单项选择题A chart with a natural scale of 1:160，000 is classified as a（）.

A.sailing chart
B.general chart
C.coast chart
D.harbor chart

单项选择题A chart projection depicting the poles and a small area on either side of a connecting meridian，that is sometimes used for star charts，is the（）.

A.azimuthal gnomonic projection
B.Lambert conformal projection
C.transverse Mercator projection
D.polyconic projection

单项选择题A chart position enclosed by a square is a(n)（）.

A.fix
B.estimated position
C.dead reckoning position
D.running fix