单项选择题
A.PORIORAOR-EAOR-W B.A1A2A3A4 C.16个航行警告区和气象警告区 D.24个NAVTEX区
A.①②③ B.②④③ C.⑥④③ D.④⑤①
A.①②③ B.②③⑤ C.②③④ D.④⑥