Complex sentence: Lawrence L. Langer holds an extensive teaching background that began at the University of Connecticut in 1957, where he was an English instructor until 1958, when he began teaching at Simmons College as an Instructor to a Professor of English until 1976.
Split into simpler sentences: Lawrence L. Langer began teachinf at the University of Connecticut in 1957, where he was an English instructor until 1958. Then, he taught at Simmons College as an Instructor to a Professor of English until 1976.