A. Land first sighted when vessel approaching from seaward B. Land last sighted when vessel leaving from a port C. in sight of one another when vessel underway D. in sight of an island during a ship on her voyage
A. 彩色电视信号较强 B. 彩色电视信号较弱 C. 亮度和饱和度太强 D. 亮度和饱和度太弱