user: ### NOW ANSWER:
Question: Which Capacity has a City of London, and a Stadium of Queen's Club?
Columns: ['Rank', 'Stadium', 'Capacity', 'City', 'Country']
Types: ['text', 'text', 'real', 'text', 'text']
Sample row: ['1', 'Arthur Ashe Stadium', 23200.0, 'New York City', 'United States']
SQL:

assistant: SELECT AVG("Capacity") FROM "Table" WHERE "City" = 'London' AND "Stadium" = 'Queen''s Club';