user: Question: What's the subject of 20 questions in those issues where Jillian Grace is the centerfold model?
Columns: ['Date', 'Cover model', 'Centerfold model', 'Interview subject', '20 Questions', 'Pictorials']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['1-05', 'Jenny McCarthy', 'Destiny Davis', 'Toby Keith', 'James Caan', 'Jenny McCarthy']
SQL:

assistant: SELECT "20 Questions" FROM "Table" WHERE "Centerfold model" = 'Jillian Grace';