单项选择题
The COSPAS-SARSAT system can provide distress alerts to the appropriate authorities（）.
A.anywhere in the world B.at sea C.in the air D.ashore
单项选择题 The COSPAS-SARSAT 406mhz system was adopted as an element of the GMDSS by IMO in（）.
单项选择题 which function is the most important one of the GMDSS.（）
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.
