Cepheids
(cepheid 的复数) 造父变星
🗣️ 情景例句
No, thanks.
不用了， 谢谢。
Is it direct train?
这是直达车吗？
To get a full appreciation of what this means we must turn first to some recent human inventions.
要透彻理解这句话的意义，我们应先回顾一下人类最近的几项发明。