user: Question: Who was the opponent on February 28, 1991
Columns: ['#', 'Date', 'at/vs.', 'Opponent', 'Score', 'Attendance', 'Record']
Types: ['real', 'text', 'text', 'text', 'text', 'real', 'text']
Sample row: [1.0, 'January 5, 1991', 'at', 'Detroit Turbos', '8 - 18', 6847.0, 'Loss']
SQL:

assistant: SELECT "Opponent" FROM "Table" WHERE "Date" = 'February 28, 1991';