单项选择题
The difference between a class A and a class B EPIRB is that the class A EPIRB（）.
A.operates on both military and civilian aircraft distress frequencies B.transmits both an alerting signal and a homing signal C.must be the float free type and automatically activated D.operates with a greater output of signal power
单项选择题 The Consol navigation system，used in Russian and Northern European waters，can be used（）.
单项选择题 The Class A EPIRB transmits a signal（）.
单项选择题 Survival craft EPIRBs (Class S) are（）.
