单项选择题
Approaching an anchorage in fog，you hear one short，one prolonged，and one short blast in that sequence on a ship’s whistle． This indicates（）.
A.A vessel towed B.A vessel not under command and unable to maneuver C.A vessel anchored giving warning of her position D.A vessel stopped dead in the water
单项选择题 An occulting light is one in which（）.
单项选择题 An inconspicuous，partly submerged vessel or object being towed，where the length of tow is 100 meters，shall show（）.
单项选择题 An all-round flashing yellow light may be exhibited by a(n)（）.
