CREATE TABLE "24_hours_of_le_mans_results" (
  "year" real,
  "team" text,
  "co_drivers" text,
  "class" text,
  "laps" real,
  "pos" text,
  "class_pos" text
);

Question: Which Class has Laps of 31?
SQL: SELECT "class" FROM "24_hours_of_le_mans_results" WHERE "laps"=31;