单项选择题
When underway and proceeding ahead，as the speed increases，the pivot point tends to（）.
A.move aft B.move forward C.move lower D.remain stationary
单项选择题 When towing in an open seaway，it is important to use a towing line（）.
单项选择题 When towing astern，increased catenary will（）.
单项选择题 When steering a tow downstream around the shape of a sand bar，and staying on the proper side of the buoys，an operator should be cautious of（）.
