Complex sentence: Between 1960 and 1962, Folkman served in the United States Navy as a lieutenant, where he studied blood vessel growth at the National Naval Medical Center in Bethesda, Maryland.
Split into simpler sentences: Between 1960 and 1962, Folkman served in the United States Navy, as a Lieutenant, where he studied blood vessel growth. He worked at the National Naval Medical Center in Bethesda, Maryland.