4. The number of integer solutions $(x, y)$ for the equation $\frac{1}{x}+\frac{1}{y}=\frac{1}{7}$ is $(\mathrm{x})$.
A. 5
B. 6
C. 7
D. 8
【Answer】 $\mathrm{A}$
【Solution】【Detailed】 $(x, y)=(-42,6),(6,-42),(8,56),(14,14),(56,8)$, a total of 5 pairs. When $x=7$, there is no solution; when $x \neq 7$, $y=\frac{7 x}{x-7}$, so $x-7 \mid 7 x$, thus $x-7 \mid 49$, hence $x=-42,6,8,14,56$. In summary, there are 5 pairs of solutions. Therefore, the answer is: $\mathrm{A}$