单项选择题 （）conveys a signal of desired rudder angle from the bridge and activates the power unit and transmission system unit the desired angle is reached.

单项选择题 In the constant-tension mooring, the mooring lines holding the ship to the pier will maintain a constant tension even with changes in tide or ship’s draft, （）.

单项选择题 （）is put into use in the late years to maintain a preset tension in a mooring line after a ship has been tied up at a pier.