Question: The Rake's Progress and Stiffelio are both operas in how many acts?
Sentence (from "The Rake's Progress"): The libretto, written by W. H. Auden and Chester Kallman, is based loosely on the eight paintings and engravings "A Rake's Progress" (1733–1735) of William Hogarth, which Stravinsky had seen on 2 May 1947, in a Chicago exhibition.
Relevant evidence: No