user: Question: Which Surface has an Opponent of Rafael Nadal, and an Event of 2?
Columns: ['!Event', 'Round', 'Surface', 'Winner', 'Opponent', 'Result']
Types: ['real', 'text', 'text', 'text', 'text', 'text']
Sample row: [1.0, 'Wimbledon', 'Final', 'Grass', 'Roger Federer', 'Andy Roddick']
SQL:

assistant: SELECT "Surface" FROM "Table" WHERE "Opponent" = 'Rafael Nadal' AND "!Event" = 2.0;