col : rank | nation | gold | silver | bronze | total row 1 : 1 | cuba | 4 | 3 | 2 | 9 row 2 : 2 | canada | 4 | 2 | 1 | 7 row 3 : 3 | united states | 2 | 0 | 2 | 4 row 4 : 4 | mexico | 1 | 1 | 0 | 2 row 5 : 5 | ecuador | 1 | 0 | 0 | 1 row 6 : 6 | argentina | 0 | 4 | 3 | 7 row 7 : 7 | brazil | 0 | 2 | 2 | 4 row 8 : 8 | chile | 0 | 0 | 1 | 1 row 9 : 8 | venezuela | 0 | 0 | 1 | 1 row 10 : total | total | 12 | 12 | 12 | 36
which countries have won gold medals? of these countries, which ones have never won silver or bronze medals?
united states, ecuador
Rank Nation Gold Silver Bronze Total
of these countries, which ones have never won silver or bronze medals?
1 Cuba 4 3 2 9
2 Canada 4 2 1 7
3 United States 2 0 2 4
4 Mexico 1 1 0 2
5 Ecuador 1 0 0 1
6 Argentina 0 4 3 7
7 Brazil 0 2 2 4
8 Chile 0 0 1 1
8 Venezuela 0 0 1 1
Total Total 12 12 12 36
United States Ecuador
of these countries, which ones have never won silver or bronze medals? || which countries have won gold medals?