What is the previous team of the United States player who had 2 NBA years and played the F position?
CREATE TABLE "selections" (
  "pos" text,
  "nationality" text,
  "previous_team" text,
  "nba_years_a" real,
  "career_with_the_franchise_b" text
);
SELECT "previous_team" FROM "selections" WHERE "nationality"='united states' AND "nba_years_a"=2 AND "pos"='f';