7. If the numbers $1,2, \cdots, 9$ are respectively filled into the nine cells of a $3 \times 3$ grid, such that the sum of the three numbers in each row and each column is a prime number, then the filling method is $\qquad$ .
7. \begin{tabular}{|l|l|l|} \hline 1 & 7 & 9 \\ \hline 2 & 6 & 3 \\ \hline 8 & 4 & 5 \\ \hline \end{tabular} .
(Answer is not unique)