user: Question: When has a surface of Road and an event of Half marathon?
Columns: ['Surface', 'Event', 'Time ( h : m : s )', 'Date', 'Place']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['Outdoor track', '1500 m', '3:38.40', '15 July 2010', 'Lappeenranta']
SQL:

assistant: SELECT "Date" FROM "Table" WHERE "Surface" = 'Road' AND "Event" = 'Half marathon';