curve tracing的用法和樣例：
例句
- The curve traced by a point on the circumference of a circle that rolls on a straight line.
圓滾線(xiàn)，擺線(xiàn)圓周上任一點(diǎn)在一條直線(xiàn)上滾動(dòng)時(shí)所形成的曲線(xiàn) - A curve traced by a point on or connected with a circle as the circle rolls along a fixed straight line.
旋轉線(xiàn)，次擺線(xiàn)圓在固定直線(xiàn)上滾動(dòng)時(shí)，圓上一點(diǎn)或與圓相連的一點(diǎn)的弧形軌跡
