user: Question: On which day were the subtotal hours 9:30?
Columns: ['Date', 'ID code of his Zero Fighter', 'Flight hours', 'Count', 'Sub-total']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['Apr.3 (Sat.)', 'T2-187', '1:30', '1', '1:00']
SQL:

assistant: SELECT "Date" FROM "Table" WHERE "Sub-total" = '9:30';