Which opera, if any,  Venus and Adonis or Bluebeard's Castle has more acts ?
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. The libretto was written by Béla Balázs, a poet and friend of the composer, and is written in Hungarian, based on the French literary tale "La Barbe bleue" by Charles Perrault. The opera lasts only a little over an hour and there are only two singing characters onstage: Bluebeard ("Kékszakállú "), and his new wife Judith ("Judit " ); the two have just eloped and Judith is coming home to Bluebeard's castle for the first time.
Sir John in Love Sir John in Love is an opera in four acts by the English composer Ralph Vaughan Williams. The libretto, by the composer himself, is based on Shakespeare's "The Merry Wives of Windsor" and supplemented with texts by Philip Sidney, Thomas Middleton, Ben Jonson, and Beaumont and Fletcher. The music deploys English folk tunes, including "Greensleeves". Originally titled "The Fat Knight", the opera premiered at the Parry Opera Theatre, Royal College of Music, London on 21 March 1929. Its first professional performance was on 9 April 1946 at Sadler's Wells Theatre.