user: Question: What is Opposing Teams, when Against is "20", and when Venue is "Twickenham , London"?
Columns: ['Opposing Teams', 'Against', 'Date', 'Venue', 'Status']
Types: ['text', 'real', 'text', 'text', 'text']
Sample row: ['Scotland', 20.0, '03/02/2007', 'Twickenham , London', 'Six Nations']
SQL:

assistant: SELECT "Opposing Teams" FROM "Table" WHERE "Against" = 20.0 AND "Venue" = 'Twickenham , London';