单项选择题
（）is designed to send an automatic distress alert when a ship sinks suddenly.
A.Lifeboat B.A survival craft C.An EPIRB D.A SART
单项选择题 （）process the distress signal from EPIRB to determine its position and identity.
单项选择题 It is（）for mariners to combine the SART with a float-free satellite EPIRB.
单项选择题 （）is a space system using one or more artificial earth satellites.
