Table: fa_cup_match_21
Columns: tie_no
home_team
score
away_team
attendance

Question: What is sheffield united's away team?
SQL: SELECT "away_team" FROM fa_cup_match_21 WHERE "home_team" = 'sheffield united'

Question: How many people attended the Away team of middlesbrough?
SQL: SELECT COUNT("attendance") FROM fa_cup_match_21 WHERE "away_team" = 'middlesbrough'

Question: Which Score has an Away team of middlesbrough?
SQL: SELECT "score" FROM fa_cup_match_21 WHERE "away_team" = 'middlesbrough'