user: Question: Who was the opponent when the Phillies played on April 28?
Columns: ['Date', 'Opponent', 'Score', 'Loss', 'Save', 'Attendance', 'Record']
Types: ['text', 'text', 'text', 'text', 'text', 'real', 'text']
Sample row: ['April 2', '@ Marlins', '8–2', 'Carl Pavano (0–1)', 'None', 10534.0, '2–0']
SQL:

assistant: SELECT "Opponent" FROM "Table" WHERE "Date" = 'April 28';