Align along a line

    Steps:

   1、Select the nodes and enter the node editing status.

   2、Open the “Coordinate Axe”. While holding the right button of the mouse, drag the circle in front of the X-axe  to rotate the select object to given     direction.

   3、Click the box in the rear of the Y-axe, input the figure “zero” in the input box and then press the “enter” key.