It forms these arches because when the wheel has rotated by a full turn, then you're basically back at the same situation, except a bit further along the route.

它形成这些拱形，是因为车轮完整的转动了一圈，然后就回到了原处，除了移动了一段路径。

youdao

It forms these arches because when the wheel has rotated by a full turn, then you're basically back at the same situation, except a bit further along the route.

它形成这些拱形，是因为车轮完整的转动了一圈，然后就回到了原处，除了移动了一段路径。

youdao