单项选择题
A fog signal consisting of one prolonged blast followed by four short blasts would indicate thepresence of a（）.
A.vessel being towed B.fishing vessel engaged in trawling C.vessel at anchor warning of her location D.power-driven pilot vessel on station underway
单项选择题 A flashing light is a light that（）.
单项选择题 A drawbridge may use visual signals to acknowledge a vessel’s request to open the draw. Which signal indicates that the draw will NOT be opened immediately?（）.
单项选择题 A 95-meter vessel aground sounds which fog signal? （）
