CREATE TABLE table_21721 ("Class" TEXT, "Part 1" TEXT, "Part 2" TEXT, "Part 3" TEXT, "Part 4" TEXT, "Verb meaning" TEXT)

What class is the verb wich its part 3 is heldu
SELECT "Class" FROM table_21721 WHERE "Part 3" = 'heldu'
SELECT "Class" FROM "table_21721" WHERE "Part 3" = 'heldu'