单项选择题 A Danforth lightweight anchor does NOT hold well in which type of bottom? （）

单项选择题 Your 15-meter tug is underway and crossing a deep and narrow channel. A large container vessel is off your port bow on a steady bearing. Which statement is TRUE concerning this situation? （）.

单项选择题 Your vessel has anchored in a channel known to have strong tidal currents. To check your position you take a round of bearings，one of which is a range in line. One hour later the bearing on the lights in range opens up. This indicates the ship is（）.