Complex sentence: The constitution was approved by the Cortes Generales on October 31,1978, and by the Spanish people in a referendum on December 6,1978, before being promulgated by King Juan Carlos on December 27.
Split into simpler sentences: The constitution was approved by the Cortes Generales on October 31,1978, and by the Spanish people in a referendum on December 6,1978. Finally, it was promulgated by King Juan Carlos on December 27.