单项选择题
which function is the most important one of the GMDSS.（）
A.alerting B.on-scene communication C.safety information D.general communication
单项选择题 The quality of EGC message is（）affected by the position of the ship, the time of reception and climatic condition.
单项选择题 The information flow of the MSI broadcast must be controlled（）.
单项选择题 If EGC receiver shares a same antenna with INMARSAT MES, it means that it can receive MSI（）.
