user: Question: What is the listed Tonnage that has U-boats destroyed (KuK) of 2 and Ships sunk (Pola) of (not recorded)?
Columns: ['Date', 'Ships sunk (Pola)', 'Tonnage', 'U-boats destroyed (KuK)', 'U-boats destroyed (Pola)']
Types: ['real', 'text', 'text', 'text', 'text']
Sample row: [1914.0, 'n/a', 'n/a', 'none', 'n/a']
SQL:

assistant: SELECT "Tonnage" FROM "Table" WHERE "U-boats destroyed (KuK)" = '2' AND "Ships sunk (Pola)" = '(not recorded)';