Complex sentence: He made his debut at the San Francisco Opera in 1961, as Edgardo, and at the Metropolitan Opera in 1970, as Pollione, opposite Joan Sutherland and Marilyn Horne.
Split into simpler sentences: He made his debut at the San Francisco Opera in 1961, as Edgardo. His Metropolitan Opera was in 1970, as Pollione, opposite Joan Sutherland and Marilyn Horne.