Conics
n. 锥线法, 锥线论
🗣️ 情景例句
Language is for the exchange of idea, for communication.
语言是用来交换思想，用来交流的。
Steel ball
钢珠
I can't understand why he is being so selfish. He isn't usually like that.
我不明白他此刻怎么这么自私。他平时不这样。