Complex sentence: Thant refuted the idea in his memoirs, listing three primary objections: first, the Congo had been admitted into the UN in 1960 as a "unified state" with the written agreement of Tshombe.
Split into simpler sentences: Thant refuted the idea in his memoirs, listing three primary objections. First, the Congo had been admitted into the UN in 1960 as a "unified state" with the written agreement of Tshombe.