Epicycloid
n. [數]圓外旋輪線, 外擺線
??? 情景例句
The economy is booming in this country.
這個國家的經濟形勢一片大好。
Excuse me. Where is No.5 Street?
對不起，第五大街在哪兒？
It is said that a new policy is being put into practice in your foreign trade.
據說你們正在實施一種新的對外貿易政策。