CREATE TABLE table_name_6 (proposed VARCHAR2, listed VARCHAR2, county VARCHAR2)

When was the site listed 03/31/1989 in rockingham county proposed?
SELECT proposed FROM table_name_6 WHERE listed = "03/31/1989" AND county = "rockingham"
SELECT "proposed" FROM "table_name_6" WHERE "03/31/1989" = "listed" AND "county" = "rockingham"