Complex sentence: Since the nation's official debut in 1952, Thai athletes have appeared in every edition of the Summer Olympic Games except the 1980 Summer Olympics in Moscow, because of its partial support of the US-led boycott.
Split into simpler sentences: Since the nation's official debut in 1952, Thai athletes have appeared in every edition of the Summer Olympic Games. Thailand did not attend the 1980 Summer Olympics in Moscow, because of its partial support to the US-led boycott.