Checkers only move diagonally which explains why you can't capture A7. To capture a piece, you must jump over it to the space beyond it, which is why you can't capture F8 (it is on the edge of the board).
(sakla) If you don't want other users to know what you are doing you can change into cloak mode in Settings (paying members only). (pauloaguia) (Bütün ipuçlarını göster)