CREATE TABLE "doubles_20_13_7" (
  "outcome" text,
  "date" text,
  "tournament" text,
  "surface" text,
  "partner" text,
  "opponents" text,
  "score" text
);

Question: Which partners were runner-up in the tournament in Mons, Belgium?
SQL: SELECT "partner" FROM "doubles_20_13_7" WHERE "outcome"='runner-up' AND "tournament"='mons, belgium';