Quadric
a. 二次的\\nn. 二次曲面
🗣️ 情景例句
Hi. Welcome.
嗨， 欢迎你 。
We don't go dancing very often.
我们不经常跳舞。
When they had gone, the driver of the car came towards him.
他们走后，汽车司机向他走来，