单项选择题
A.the direction of the true wind B.true north C.the beam on the windward side D.the beam on the lee side
In modern fathometers the sonic or ultrasonic sound wav...
单项选择题In modern fathometers the sonic or ultrasonic sound waves are produced electrically by means of a(n)（）.
A.transmitter B.transducer C.transceiver D.amplifier
In mid-ocean，the characteristics of a wave are determin...
单项选择题In mid-ocean，the characteristics of a wave are determined by three factors. What is NOT one of these factors?（）.
A.Effect of the moon's gravity B.Fetch C.Wind velocity D.Length of time a wind has been blowing
In a tropical cyclone，in the Northern Hemisphere，a vess...
单项选择题In a tropical cyclone，in the Northern Hemisphere，a vessel hove to with the wind shifting counterclockwise is（）.
A.ahead of the storm center B.in the dangerous semicircle C.in the navigable semicircle D.directly in the approach path of the storm
