单项选择题 A towing vessel should be on the crest of a wave at the same time as its tow and in the trough at the same time. The term used to describe this is（）.

单项选择题 A towboat has the same draft as the barges it is pushing ahead. If the distance from the stern of the towboat to the head of the tow is 260m，where is the approximate location of the pivot point of the unit?（）

单项选择题 A tow that veers to the side on the end of the towline is said to（）.