question: The American soprano that sang in "West Side Story" dubbed for who in a 1956 film adaptation?
answer: Deborah Kerr
context: Title: Getting to Know You (song)
  Passage: "Getting to Know You" is a show tune from the 1951 Rodgers and Hammerstein musical "The King and I".  It was first sung by Gertrude Lawrence in the original Broadway production and later by Marni Nixon who dubbed for Deborah Kerr in the 1956 film adaptation.  In the show, Anna, a British schoolteacher who has been hired as a governess, sings the song as she strikes up a warm and affectionate relationship with the children and the wives of the King of Siam.
  Title: Kenton's West Side Story
  Passage: Kenton's West Side Story is an album by Stan Kenton that won the Grammy Award in 1962 for Best Jazz Performance – Large Group (Instrumental).  The album was recorded in 1961 and released quickly to take advantage of the movie premiere of the musical "West Side Story".  Kenton won his first Grammy Award.  He won again the next year in the same category.  "Kenton's West Side Story" peaked at No. 16 on the "Billboard" magazine album chart.
  Title: Marni Nixon
  Passage: Margaret Nixon McEathron (February 22, 1930 – July 24, 2016), known professionally as Marni Nixon, was an American soprano and playback singer for featured actresses in movie musicals.  She was best known for dubbing the singing voices of the leading actresses in films, including "The King and I", "West Side Story", and "My Fair Lady".
citations: Getting to Know You (song) Marni Nixon