Complex sentence: He left Belgium for North America in 1940 and was music director of the Montreal Symphony Orchestra from 1941 to 1952 and also music director of the Chicago Symphony Orchestra from 1943 to 1947.
Split into simpler sentences: He left Belgium for North America in 1940 and was music director of the Montreal Symphony Orchestra from 1941 to 1952. He was also music director of the Chicago Symphony Orchestra from 1943 to 1947.