单项选择题
Before switching on gyro-compass，you should make sure that the power supply on board is（）.
A.high or low
B.AC or DC
C.strong or weak
D.on or off
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相关考题
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单项选择题
Calibration Stations give special transmissions for the calibration of ship’s（）.
A.gyro-compass
B.marine radar
C.DF
D.navigational satellite -
单项选择题
To obtain accuracy in fixing by DF cross bearings，（）should be used.
A.two stations，including one on the nearest coast
B.two stations，including one on the nearer coast
C.three stations，including one on the farthest coast
D.three stations，including one on the nearest coast -
单项选择题
To obtain accuracy in fixing by DF，（）and three stations should be used.
A.parallel bearings
B.long-range bearings
C.short-range bearings
D.cross bearings
