單項選擇題

The numeral in the center of a wind rose circle on a pilot chart indicates the （）.

A.total number of observations
B.average wind force on the Beaufort scale
C.average wind force in knots
D.percentage of calms

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單項選擇題

The maximum difference between mean time and apparent time is （）.

A.equal to the longitude expressed in time units
B.about 16 minutes
C.the difference between the GHA of mean sun and the first point of Aries
D.15°of arc

單項選擇題

The description Racon beside an illustration on a chart would mean a （）.

A.radar conspicuous beacon
B.circular radiobeacon
C.radar transponder beacon
D.radar calibration beacon