CREATE TABLE table_47435 ("Year" FLOAT, "Award" TEXT, "Category" TEXT, "Nominated work" TEXT, "Result" TEXT)

What categories had a Nominated work of yerma before 1992?
SELECT "Category" FROM table_47435 WHERE "Year" < '1992' AND "Nominated work" = 'yerma'
SELECT "Category" FROM "table_47435" WHERE "Nominated work" = 'yerma' AND "Year" < '1992'