单项选择题 A power-driven fishing vessel is underway on the high seas and is not engaged in fishing. Which of the following factors determines what lights she will show?（）.

单项选择题 A power driven vessel when towing and the length of the tow exceeds 200 meters shall exhibit during daylight hours where they can best be seen which of the following shapes? （）

单项选择题 A fog signal consisting of one prolonged blast followed by four short blasts would indicate thepresence of a（）.