user: Question: When did the 55 kg participant race?
Columns: ['Result', 'Date', 'Race', 'Venue', 'Group', 'Distance', 'Weight (kg)', 'Jockey', 'Winner/2nd']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Won', '29 Dec 2004', '3yo Hcp Restricted Maiden', 'Pinjarra', 'NA', '1200 m', '55', 'K. Forrester', '2nd - Hello Doctor']
SQL:

assistant: SELECT "Date" FROM "Table" WHERE "Weight (kg)" = '55';