例句：
The axis of a circle is its diameter.
圆的对称中心线就是直径。
He used a rope to mark off the circle.
他用一根绳子把这个圈围了起来。
She walked clockwise around the circle.
她绕着圈顺时针走。
The line cuts the circle at two points.
那条线与圆相交于两点。
She walked the horse round in a circle.
她牵着马兜圈子。