单项选择题
A.complete service B.partial controlled C.quite new D.total co-ordinated
If no distress acknowledgement is received（）a DSC distr...
单项选择题If no distress acknowledgement is received（）a DSC distress call transmission, then the ship in distress may repeat the DSC distress call attempt after a delay of between 3.5 and 4.5 minutes from the beginning of the initial call.
A.relevant to B.relate to C.in response to D.in relation to
What’s the abbreviation for the World Meteorological Or...
单项选择题What’s the abbreviation for the World Meteorological Organization?（）
A.WMO B.IHO C.IMO D.WARC
Geostationary satellites are the artificial satellites ...
单项选择题Geostationary satellites are the artificial satellites which（）.
A.always move slowly B.are in one place only C.sometime move sometime don‟t move D.are synchronizing with the movement of the earth
