CREATE TABLE table_204_939 (id NUMBER, "year" NUMBER, "chassis" CLOB, "engine" CLOB, "start" CLOB, "finish" CLOB)

what chassis is previous to year 1989 ?
SELECT "chassis" FROM table_204_939 WHERE "year" = 1989 - 1
SELECT "chassis" FROM "table_204_939" WHERE "year" = 1988