user: Question: What was the surface played on when they were a Runner-up in 2007?
Columns: ['Outcome', 'Year', 'Championship', 'Surface', 'Partner', 'Opponents in the final', 'Score in the final']
Types: ['text', 'real', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Winner', 1999.0, 'French Open', 'Clay', 'Piet Norval', 'Larisa Neiland Rick Leach', '6–3, 3–6, 6–3']
SQL:

assistant: SELECT "Surface" FROM "Table" WHERE "Outcome" = 'Runner-up' AND "Year" = 2007.0;