Table: t_1943_vfl_match_4
Columns: home_team
home_team_score
away_team
away_team_score
venue
crowd
date

Question: Who was Melbourne's home team opponent?
SQL: SELECT "home_team" FROM t_1943_vfl_match_4 WHERE "away_team" = 'melbourne'

Question: Who was Richmond's away team opponent?
SQL: SELECT "away_team" FROM t_1943_vfl_match_4 WHERE "home_team" = 'richmond'