The Orthodox Church reads the Scriptures on a single annual cycle that turns around two great anchors — Pascha (Easter) and the fixed feasts of the Mother of God. There are no Years A, B, and C; the same Apostolos and Gospel return each year on the same Sunday.
Here are the Twelve Great Feasts, the Sundays of the Triodion and Great Lent, the days of Holy Week, the Paschal season, and the Sundays after Pentecost — 75 sets of readings in all.