What is Opposing Teams, when Against is "20", and when Venue is "Twickenham , London"?
CREATE TABLE "2007" (
  "opposing_teams" text,
  "against" real,
  "date" text,
  "venue" text,
  "status" text
);
SELECT "opposing_teams" FROM "2007" WHERE "against"=20 AND "venue"='twickenham , london';