CREATE TABLE table_51622 ("Home team" TEXT, "Home team score" TEXT, "Away team" TEXT, "Away team score" TEXT, "Venue" TEXT, "Crowd" FLOAT, "Date" TEXT)

Which away team played at MCG?
SELECT "Away team" FROM table_51622 WHERE "Venue" = 'mcg'
SELECT "Away team" FROM "table_51622" WHERE "Venue" = 'mcg'