Complex sentence: MacMillan served as Provost of Trinity College at the University of Toronto from 2002-2007, when she was appointed Warden of St Antony's College at Oxford University in 2007.
Split into simpler sentences: MacMillan served as Provost of Trinity College at the University of Toronto from 2002-2007. She was appointed Warden of St Antony's College at Oxford University in 2007.