CREATE TABLE "round_4" (
  "home_team" text,
  "home_team_score" text,
  "away_team" text,
  "away_team_score" text,
  "venue" text,
  "crowd" real,
  "date" text
);

Question: Which away team played at MCG?
SQL: SELECT "away_team" FROM "round_4" WHERE "venue"='mcg';

Question: What was the date when Geelong was the home team?
SQL: SELECT "date" FROM "round_4" WHERE "home_team"='geelong';