user: Question: What is Opponents in Final, when Partner is "Jill Hetherington", and when Year is after 1988?
Columns: ['Outcome', 'Year', 'Championship', 'Surface', 'Partner', 'Opponents in final', 'Score in final']
Types: ['text', 'real', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Runner-up', 1988.0, 'US Open', 'Hard', 'Jill Hetherington', 'Gigi Fernández Robin White', '6–4, 6–1']
SQL:

assistant: SELECT "Opponents in final" FROM "Table" WHERE "Partner" = 'Jill Hetherington' AND "Year" > 1988.0;