a train of ideas的用法和样例：
- A succession of ideas; a train of thought.
- The pop star was followed by a train of admirers.
- The pop star is followed by a train of admirers.
- She fell into a train of melancholy thoughts.
- A train of antiquated coaches was waiting for us at the siding.
- A train of attendants, as of a distinguished person; a retinue.