The answer here is orbit, which usually follows a curved track around something in space.

答案是orbit，它通常指太空中围绕着某物的弯曲的路径。

The arch's solution operates more like a vertical tramway, with visitors entering one of eight horizontal compartments which proceed up one leg of the arch along curved tracks.

拱门的解决方案更像是垂直的缆车，游客可以进入八个水平分隔厢中的一个，沿着弧形轨道沿着拱门的一条腿向上走。

Horrified, transfixed, Frank stared as its undulating body cut a wide, curving track through the thick dust on the floor, coming closer and closer -- What was he to do?

弗兰克吓得呆若木鸡，站在那里望着它波浪般起伏的身体，在地板上厚厚的灰尘中留下蜿蜒曲折的、宽宽的轨迹，慢慢地越来越近--他怎么办呢？