单项选择题
A.ETA pilot station has been given
B.ETA pilot station will be given afterwards
C.ETA pilot station was not given
D.ETA pilot station is given
单项选择题 Data relating to the direction and velocity of rotary tidal currents can be found in the （）.
单项选择题 Coral atolls，or a chain of islands at right angles to the radar beam，may show as a long line rather than as individual targets due to （）.
单项选择题 Before a Master relieves a Pilot of the conn，the （）.