CREATE TABLE table_31715 ("Week" FLOAT, "Date" TEXT, "Opponent" TEXT, "Result" TEXT, "Attendance" FLOAT)

Tell me opponent for result of w 33-31
SELECT "Opponent" FROM table_31715 WHERE "Result" = 'w 33-31'
SELECT "Opponent" FROM "table_31715" WHERE "Result" = 'w 33-31'