Table: juliet_stevenson_awards
Columns: year
award
category
nominated_work
result

Question: How many years had the best actress in a Revival category?
SQL: SELECT COUNT("year") FROM juliet_stevenson_awards WHERE "category" = 'best actress in a revival'

Question: What categories had a Nominated work of yerma before 1992?
SQL: SELECT "category" FROM juliet_stevenson_awards WHERE "year" < 1992 AND "nominated_work" = 'yerma'