问题
单项选择题
A(n)（）indicates that there is serious danger for vessel, crew and passenger.
A.distress alert
B.urgency message
C.safety message
D.routine message
答案
参考答案：B
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A(n)（）indicates that there is serious danger for vessel, crew and passenger.
A.distress alert
B.urgency message
C.safety message
D.routine message
参考答案：B