Complex sentence: In 1966-67, Hoover attended the Millard Preparatory School in Bandon, Oregon, which prepared him for entering the United States Air Force Academy, where he was a cadet from 1967 to 1969.
Split into simpler sentences: In 1966-67, Hoover attended the Millard Preparatory School in Bandon, Oregon. Millard prepared him for entering the United States Air Force Academy, where he was a cadet from 1967 to 1969.