lǎo / shī / yòng / pāo / wù / xiàn / lái / shuō / míng / yuán / zhuī / qū / xiàn / de / jī / běn / xìng / zhì

老师用抛物线来说明圆锥曲线的基本性质。

The teacher used a parabola to explain the basic properties of conic sections.