1. The rocket flew into the firmament.
火箭飞向宇宙。
2. Astronomers study galaxies in the firmament.
天文学家研究宇宙中的星系。
3. Stars can be seen in the firmament at night.
夜空中可以看到星星。
4. The firmament is full of unknown mysteries.
宇宙充满了未知的奥秘。
5. People observe the firmament through telescopes.
人们通过望远镜观察宇宙。