单项选择题
A.the distance of visibility
B.1/2 the distance of visibility
C.a distance appropriate to the existing circumstances and conditions
D.the distance that it would require for the propeller to go from full ahead to full astern
单项选择题 The distress message of a ship should include considerable information which might facilitate the rescue. This information should（）.
单项选择题 Several merchant ships are arriving at the scene of a distress incident. One of the them must assume the duties of the Coordinator Surface Search (CSS). Which of the following statements is TRUE? （）
单项选择题 If your vessel is underway in fog and you hear one prolonged and three short blasts，this indicates a（）.