Question: Wins smaller than 0 had what sum of year?
SQL: SELECT SUM("Year") FROM "2-15128023-2" WHERE "Wins" < 0.0;

Question: Class of 125cc, and a Year smaller than 1966 had what lowest wins?
SQL: SELECT MIN("Wins") FROM "2-15128023-2" WHERE "Class" = '125cc' AND "Year" < 1966.0;

Question: Class of 500cc, and a Wins smaller than 0 had what average year?
SQL: SELECT AVG("Year") FROM "2-15128023-2" WHERE "Class" = '500cc' AND "Wins" < 0.0;