user: Question: Which Surface has Semifinalists of Wally Masur MaliVai Washington?
Columns: ['Tournament', 'Surface', 'Week', 'Winner and score', 'Finalist', 'Semifinalists']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Indian Wells', 'Hard', 'March 2', 'Michael Chang 6–3, 6–4, 7–5', 'Andrei Chesnokov', 'Michael Stich Francisco Clavet']
SQL:

assistant: SELECT "Surface" FROM "Table" WHERE "Semifinalists" = 'Wally Masur MaliVai Washington';