单项选择题 A twin-screw vessel with a single rudder is making headway. The engines are full speed ahead. There is no wind or current. Which statement is FALSE? （）

单项选择题 A tug may be in danger of tripping when（）.

单项选择题 A tug is best positioned for towing and maneuvering on rivers and other restricted waters where wave action is limited when（）.