单项选择题
In areas covered by Inmarsat HF can be used as an（）to satellite communications.
A.alternation
B.alternate
C.alter
D.alternative
点击查看答案&解析
相关考题
-
单项选择题
With the help of GMDSS（）can be alerted to a distress incident as soon as possible.
A.all ships in a large sea area
B.only the sea authorities ashore
C.the SAR units ashore and at sea
D.the port radios and the coast stations -
单项选择题
The Inmarsat system is open for use by（）countries on a non-discriminatory basis.
A.some
B.lots of
C.many
D.all -
单项选择题
Within the polar areas it is（）to see a satellite in geo-stationary orbit .
A.impossible
B.possible
C.easy
D.difficult
