Which opera, if any,  Venus and Adonis or Bluebeard's Castle has more acts ?
Venus and Adonis (opera): Venus and Adonis is an opera in three acts and a prologue by the English Baroque composer John Blow, composed in about 1683. Bluebeard's Castle: Bluebeard's Castle (Hungarian: A kékszakállú herceg vára ; literally: "The Blue-Bearded Duke's Castle") is a one-act opera by Hungarian composer Béla Bartók.
Venus and Adonis