user: ### NOW ANSWER:
Question: Marty Riessen played as a partner during a match with what kind of surface?
Columns: ['Outcome', 'Date', 'Tournament', 'Surface', 'Partner', 'Opponents', 'Score']
Types: ['text', 'real', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Runner-up', 1971.0, 'Merion , U.S.', 'Hard', 'Chuck McKinley', 'Clark Graebner Jim Osborne', '6–7, 3–6']
SQL:

assistant: SELECT "Surface" FROM "Table" WHERE "Partner" = 'Marty Riessen';