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 Emerald Isle The Emerald Isle; "or, The Caves of Carrig-Cleena", is a two-act comic opera, with music by Arthur Sullivan and Edward German, and a libretto by Basil Hood. The plot concerns the efforts of an Irish patriot to resist the oppressive "re-education" programme of the English, which has robbed the Irish of their cultural heritage. A quirky "Professor of Elocution" who is hired by the English to continue this "re-education" of the Irish switches sides to help the Irish. Romantic complications cause a confrontation between the Irish patriots and the superstitious English at the supposedly haunted caves of Carric-Cleena, and disguises are employed to hold the English off; but the professor ultimately comes up with a solution that works out happily for all.