user: Question: When was the parliament that was elected in 1509/10, and had an unknown second member, dissolved?
Columns: ['Elected', 'Assembled', 'Dissolved', '1st member', '2nd member']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['1509/10', '21 January 1510', '23 February 1510', 'unknown', 'unknown']
SQL:

assistant: SELECT "Dissolved" FROM "Table" WHERE "2nd member" = 'unknown' AND "Elected" = '1509/10';