Which chassis had Rounds of 7, and an Entrant of Ecurie Rosier?
CREATE TABLE "teams_and_drivers" (
  "entrant" text,
  "constructor" text,
  "chassis" text,
  "driver" text,
  "rounds" text
);
SELECT "chassis" FROM "teams_and_drivers" WHERE "rounds"='7' AND "entrant"='ecurie rosier';