16. (15 points) In an $m$-row $n$-column grid, it is stipulated that the horizontal rows from top to bottom are sequentially the 1st row, the 2nd row, $\cdots$, and the vertical columns from left to right are sequentially the 1st column, the 2nd column, $\cdots$. The point $(a, b)$ represents the grid point located in the $a$-th row and the $b$-th column. Figure 1 is a 4-row 5-column grid. Starting from point $A(2,3)$, following the "ri" (日) character movement of a knight in Chinese chess, it can reach the grid points $B(1,1), C(3,1), D(4,2), E(4,4), F(3,5), G(1,5)$ in the grid. If in a 9-row 9-column grid (Figure 2), starting from point $(1,1)$, following the "ri" (日) character movement of a knight in Chinese chess,
(1) Can it reach every grid point in the grid?
Answer: $\qquad$ . (Fill in "Yes" or "No")
(2) If it can, then along the shortest path to reach a certain grid point, what is the maximum number of steps needed? How many such grid points are there? Write down their positions. If it cannot, please explain the reason.
【Answer】Solution: Walking in a "日" shape means moving along the diagonal of a rectangle formed by two adjacent small squares: as shown in the figure. Therefore, every grid point can be reached.

Answer: Every grid point can be reached.

Starting from the point $(1,1)$, the points that can be reached in one move are marked as 1, and the starting point is marked as 0; then, from the points marked as 1, consider the next possible moves, and mark all such points as 2, and so on, each time moving along the diagonal of a rectangle formed by two adjacent small squares. As shown in the figure below: Therefore, the maximum number of steps is 6, and the grid points are $(7,9)$, $(8,8)$, $(9,7)$, and $(9,9)$. 

Answer: The maximum number of steps is 6, and the grid points are $(7,9)$, $(8,8)$, $(9,7)$, and $(9,9)$. 

Therefore, the answer is: Yes.