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.
Fair Rosamond (opera) Fair Rosamond is an English historical opera in four acts composed by John Barnett, written in 1837 to a libretto by Charles Zachary Barnett, after the legend of Rosamund Clifford ("Fair Rosamond" or the "Rose of the World"), the 12th century mistress of King Henry II who was said to have been poisoned by the King's wife, Queen Eleanor. In his opera, Barnett effects a happier ending.