What circuit was on the date 4 May?
CREATE TABLE "grands_prix" (
  "round" real,
  "date" text,
  "grand_prix" text,
  "circuit" text,
  "125cc_winner" text,
  "250cc_winner" text,
  "moto_gp_winner" text,
  "report" text
);
SELECT "circuit" FROM "grands_prix" WHERE "date"='4 May';