user: Question: What tournament has Yvonne Vermaak as the opponent?
Columns: ['Outcome', 'Date', 'Tournament', 'Surface', 'Opponent', 'Score']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Winner', '14 February 1983', 'Hershey', 'Carpet (I)', 'Sandy Collins', '2–6, 6–0, 6–4']
SQL:

assistant: SELECT "Tournament" FROM "Table" WHERE "Opponent" = 'Yvonne Vermaak';