[单选题]Working on the frequency______is the compulsory requirements for portable radiotelephony equipment.
[单选题]On receipt of a relayed distress alert, ships in the area addressed should establish communication with the ______concerned to enable the assistance to be coordinated.
[单选题]What is the minimum GMDSS personnel requirement of drill platforms with Duplication of Equipment method operating in sea area A4?
[单选题]How to update a terminal with the ship's position?①Automatically, by using an electronic navigational device or a GPS; ②Manu-ally, by keying the position coordinates directly into the terminal at least onccevery 4 hours; ③Manually, by keying the position coordinates directly into the terminal once every day.
[单选题]______is (are) frequency (frequencies) can be used for routine DSC calling between ships, and between ship and shore respectively.