Code 7500 alerts ATC that _______ .
A.an aircraft has been hijacked
B.the failure of two-way radio communications has been encountered
C.emergency condition exists
D.false alarms have been sent out
正确答案是A
Code 7500 alerts ATC that _______ .
A.an aircraft has been hijacked
B.the failure of two-way radio communications has been encountered
C.emergency condition exists
D.false alarms have been sent out
正确答案是A