oppidan

例句：

1. 1.The oppidan is a small, round object that looks like a miniature planet.
   这个oppidan是一个小的、圆的物体，看起来像一个迷你星球。
2. 2. The oppidan was discovered by astronomers who were studying the stars.
   这个oppidan是由天文学家发现的，他们正在研究星星。
3. 3.The oppidan was used to study the properties of matter and energy.
   这个oppidan被用来研究物质和能量的性质。