Draw a picture according to "Positive Bending Distance of External Force Left, Right and Reverse" (when cutting the bar, the external force makes the left bar rotate clockwise around the cutting section, then the bending distance corresponding to this force is positive)

In the bending distance diagram, the section without external force is inclined into a straight line, and the concentrated force produces an acute angle, and the concentrated force suddenly changes.

Shear diagram, horizontal line without external force, diagonal line with uniform force, sudden change at concentrated force.