单项选择题
While moving ahead，a twin-screw ship has an advantage over a single-screw ship because （）.
A.correct trim will be obtained more easily B.drag effect will be cancelled out C.side forces will be eliminated D.speed will be increased
单项选择题 When towing astern，one way to reduce yawing of the tow is to（）.
单项选择题 When a vessel navigates in an area with a small underkeel clearance but with adequate space to take avoiding action she（）.
