user: Question: What was the surface when he played with John Alexander? 
Columns: ['Year', 'Championship', 'Surface', 'Partner', 'Opponents in final', 'Score in final']
Types: ['real', 'text', 'text', 'text', 'text', 'text']
Sample row: [1982.0, 'Australian Open', 'Grass', 'John Alexander', 'Andy Andrews John Sadri', '6–4, 7–6']
SQL:

assistant: SELECT "Surface" FROM "Table" WHERE "Partner" = 'John Alexander';