human
Considering the provided database schema and associated query, produce SQL code to retrieve the answer to the query. 
###Database Schema: Outcome, Date, Championship, Surface, Opponent in the final, Score in the final
###Question: What is Opponent In The Final, when Date is before 1991, and when Outcome is "Runner-Up"?
gpt
SELECT Opponent in the final FROM table WHERE Date < 1991 AND Outcome = runner-up