8. A light ray $l$ emitted from point $A(-3,3)$ is reflected by the $x$-axis. The straight line of the reflected ray is tangent to the circle $x^{2}+y^{2}-4 x-4 y+7=0$. Then the equation of the straight line $l$ is $\qquad$ .
$4 x+3 y+3=0$ or $3 x+4 y-3=0$.