Complex sentence: The Hungarian-born speed skater had won both long distance races at the World Championships held in Oslo in 1949 and then defected to Sweden, but he was unable to gain Swedish citizenship in time to compete in 1952.
Split into simpler sentences: The Hungarian-born speed skater had won both long distance races at the World Championships held in Oslo in 1949 and then defected to Sweden. He was unable to gain Swedish citizenship in time to compete in 1952.