user: Question: What is the number of bronze for canada and silver is less than 0?
Columns: ['Rank', 'Nation', 'Gold', 'Silver', 'Bronze', 'Total']
Types: ['real', 'text', 'real', 'real', 'real', 'real']
Sample row: [1.0, 'United States', 0.0, 1.0, 3.0, 4.0]
SQL:

assistant: SELECT SUM("Bronze") FROM "Table" WHERE "Nation" = 'canada' AND "Silver" < 0.0;