user: Question: What year was the role Nan Taylor, Alias of Nan Ellis, aka Mrs. Andrews and directed by William Keighley?
Columns: ['Year', 'Film', 'Role', 'Leading Man', 'Director']
Types: ['real', 'text', 'text', 'text', 'text']
Sample row: [1927.0, 'Broadway Nights', 'Fan dancer (uncredited)', '—', 'Joseph C. Boyle']
SQL:

assistant: SELECT "Year" FROM "Table" WHERE "Role" = 'Nan Taylor, Alias of Nan Ellis, aka Mrs. Andrews' AND "Director" = 'William Keighley';