user: Question: What is the tournament with a Hard surface and Ruben de Kleijn as the opponent?
Columns: ['Date', 'Tournament', 'Surface', 'Opponent', 'Score']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['September 25, 2000', 'Kawaguchi [ disambiguation needed ]', 'Hard', 'Leigh Holland', '6–1, 6–2']
SQL:

assistant: SELECT "Tournament" FROM "Table" WHERE "Surface" = 'Hard' AND "Opponent" = 'Ruben de Kleijn';