Hello, landlord. I am also a middle school student who just graduated. The analysis of this problem is as follows: For example, because ab is the diameter of circle O, the midpoint of ab is the center of circle O, and because circle O and bc intersect at D, od=ob, so: angle b= angle bdo, and because de is perpendicular to ac and point E, angle ced= angle aed. =90 degrees and because: de is the tangent of the circle O, and the angle ode=90 degrees (the diameter of the circle is perpendicular to its tangent), because: Angle ode= Angle ced=90 degrees, so: od is parallel to ac (the internal dislocation angle is equal, and the two straight lines are parallel), so: Angle odb= Angle C (the two straight lines are parallel, and the angle at the same position is equal) and because: Angle ODB.