 Complete the following phrase:  Ponomaryov was domit nationally in 1977, taking the 800 m indoor title and an 8001500 metres double at the Soviet Championships. He was absent in the 1978 season but returned the following year to win his last national titles over 1500 m at the Soviet Indoor Championships and Spartakiad. In his last major international outing, he took his highest honour  a 1500 m silver medal at the 