Pinning Combinations

White to move:

We have a White Bishop's blockading the Black pawn at c3; it's pinning the Black Queen at g7. That's why the White Queen can use the weak square of h6 and occupying it. Remember, a square in front of any pawns without protection or controlling by a side-pawn is a weak square. Now, how do we add one more pin to the Black's current position, the answer is Ng6! Once the White Knight is at g6, the Black pawn at h7 is pinned; what's more, it gives check to the Black King also. Since the Black Rook is blocking the Black King, the position after Ng6 is a checkmated position for Black.