Tell me the name for first elected more than 1988 and district of mason
CREATE TABLE "county_board_of_supervisors" (
  "position" text,
  "name" text,
  "party" text,
  "first_elected" real,
  "district" text
);
SELECT "name" FROM "county_board_of_supervisors" WHERE "first_elected">1988 AND "district"='mason';