7・15 Draw n segments sequentially on a plane, where the terminal point of the nth segment coincides exactly with the starting point of the 1st segment. Each segment is called a "line segment." If the starting point of one line segment coincides exactly with the terminal point of another line segment, these two line segments are called adjacent. We stipulate: two adjacent line segments cannot be drawn on the same straight line, and any two non-adjacent line segments do not intersect. A figure that meets the above conditions is called a "simple polygonal loop." As shown in the figure, the ten line segments of the simple polygonal loop we draw are distributed on five straight lines.

If all n line segments of a simple polygonal loop are distributed on six straight lines, try to find the maximum value of n, and explain the reason.

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[Solution] We prove that the maximum value of $n$ is 12.
First, we can draw a simple zigzag loop for $n=12$ (as shown in the figure). If $n>12$, since the $n$ segments are distributed on 6 lines, by the pigeonhole principle, at least one line $l$ contains at least three segments. These at least three segments are not adjacent to each other, so there are at least 6 endpoints on this line $l$, which are the intersection points of at least 6 different segments with the line $l$. These at least 6 different lines, together with $l$, make up at least 7 lines, leading to a contradiction.
Therefore, the maximum value of $n$ is 12.