nebulae

例句：

1. 1. The nebulae in the sky are fascinating to observe.
   天空中的星云令人着迷。
2. 2. The nebulae are believed to be the birthplace of stars.
   人们相信星云是恒星的诞生地。
3. 3. The study of nebulae is crucial for understanding the formation of galaxies.
   研究星云对于理解星系的形成至关重要。