Complex sentence: He was elected a member of the Central Committee at the XXIVth congress of the CPSU in 1971, became a candidate member of the Politburo in 1973 and a full member in 1976.
Split into simpler sentences: He was elected a member of the Central Committee of the Communist Party of the Soviet Union at the XXIVth congress of the CPSU in 1971. He became a candidate member of the Central Committee's Politburo in 1973 and a full member in 1976.