Complex sentence: Marvin T. Runyon (September 16 1924--May 3 2004) was an American manager at Nissan and Ford who served as chairman of the Tennessee Valley Authority and as U.S. Postmaster General.
Split into simpler sentences: Marvin T. Runyon (September 16 1924--May 3 2004) was an American business executive. He later served as chairman of the Tennessee Valley Authority and as U.S. Postmaster General.