This John Dexter production, designed by Desmond Heeley, was a parting gift to the great American soprano Beverly Sills, who bid farewell to the Met as Norina, the smart young widow at the center of Donizetti’s comedy. The sensational Alfredo Kraus sings her beloved Ernesto. Håkan Hagegård, in his Met debut role and season, is Dr. Malatesta, the man who helps the young couple trick the crusty old bachelor of the title (Gabriel Bacquier at his comical best) into a fake marriage. This being a Donizetti comedy, it all turns out perfectly well at the end—and getting there is pure operatic fun.