例句：

　　The axis of a circle is its diameter.

　　圓的對稱中心線就是直徑。

　　He used a rope to mark off the circle.

　　他用一根繩子把這個(gè)圈圍了起來。

　　She walked clockwise around the circle.

　　她繞著圈順時(shí)針走。

　　The line cuts the circle at two points.

　　那條線與圓相交于兩點(diǎn)。

　　She walked the horse round in a circle.

　　她牽著馬兜圈子。