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. It was written for the court of King Charles II at either London or Windsor. It is considered by some to be either a semi-opera or a masque, but "The New Grove" names it as the earliest known English opera.
The Minotaur (opera) The Minotaur is an opera in two acts, with 13 scenes by English composer Harrison Birtwistle to a libretto by poet David Harsent, commissioned by the Royal Opera House in London. The work, a retelling of the Greek myth of the Minotaur, premiered at the Royal Opera House on 15 April 2008 and was shown on BBC2 television on 7 June 2008. The score is modernistic, and the scenes fall into three types: bullfights; scenes between Ariadne and Theseus; and dream sequences for the Minotaur, in which the creature has the gift of speech. The opera lasts about 140 minutes, not counting the interval.