user: Question: What is Surface, when Tournament is "Sunderland , United Kingdom"?
Columns: ['Date', 'Tournament', 'Surface', 'Opponent in the final', 'Score']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['23 October 2006', 'Rodez , France', 'Hard', 'Andrey Golubev', '4–6, 6–1, 6–0']
SQL:

assistant: SELECT "Surface" FROM "Table" WHERE "Tournament" = 'Sunderland , United Kingdom';