user: Question: What categories had a Nominated work of Yerma before 1992?
Columns: ['Year', 'Award', 'Category', 'Nominated work', 'Result']
Types: ['real', 'text', 'text', 'text', 'text']
Sample row: [1984.0, 'Olivier Award', 'Best Actress in a Revival', 'Measure for Measure', 'Nominated']
SQL:

assistant: SELECT "Category" FROM "Table" WHERE "Year" < 1992.0 AND "Nominated work" = 'Yerma';