8. If 4 lines in a plane intersect each other pairwise and no three lines are concurrent, then there are $\qquad$ pairs of consecutive interior angles.
8.24.

Each line intersects with 3 other lines, forming 3 intersection points. Each 2 intersection points determine a line segment, making a total of 3 line segments. Since each line has a pair of consecutive interior angles on both sides, there are $3 \times 4=12$ line segments, and a total of 24 pairs of consecutive interior angles.