M is the point where MO is perpendicular to AB and O, and then connects CE and OE, N is the point where NP is perpendicular to AB, and CF, PF and CP connect BN and T. It is easy to prove that triangle CME is congruent with triangle OME, so CE=OE, and then called AM and S, it is easy to prove that triangle CES is congruent with OES, so S is the midpoint of CO, and it can also prove that T is the midpoint of CP, that is, TS is the midline of triangle COP. You can also check it.