spiral arm的用法和樣例：
例句
- We analyzed all sorts of problems caused by the abnormal motions of the motivity-less turning arm, and investigated its related control methods.
分析了無動力旋臂因動作不規範引起的各種問題，研究了其解決措施。 - In looking at the Carina Nebula we are seeing the genesis of star making as it commonly occurs along the dense spiral arms of a galaxy.
通過對船底座星雲的觀察，我們看到了通常沿銀河密集的旋臂所誕生恆星的起源。
