user: Question: What is 1994, when 1991 is "QF", and when Tournament is "Australian Open"?
Columns: ['Tournament', '1990', '1991', '1992', '1993', '1994', '1995', '1996', '1997', 'Career SR', 'Career Win-Loss']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Grand Slams', 'Grand Slams', 'Grand Slams', 'Grand Slams', 'Grand Slams', 'Grand Slams', 'Grand Slams', 'Grand Slams', 'Grand Slams', 'Grand Slams', 'Grand Slams']
SQL:

assistant: SELECT "1994" FROM "Table" WHERE "1991" = 'QF' AND "Tournament" = 'Australian Open';