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 want to greet someone in their native language try our Player's Dictionary, in the "more about languages" link under the flags. (pauloaguia) (Bütün ipuçlarını göster)