CREATE TABLE table_7981 ("Res." TEXT, "Record" TEXT, "Opponent" TEXT, "Method" TEXT, "Event" TEXT, "Round" FLOAT, "Time" TEXT, "Location" TEXT)

In which location did the fight last just 0:31?
SELECT "Location" FROM table_7981 WHERE "Time" = '0:31'
SELECT "Location" FROM "table_7981" WHERE "Time" = '0:31'