a single generation的用法和样例：
- Once, the copyright term spanned a single generation.
- It may have happened in the span of a single generation of Hawaiians.
- Twice in a single generation, major tragedy had come to the world, and America's national conscience felt uneasy.
- It is possible that the parasite produces and tries 100 generations during a single generation of the host.
- The letter was written on a single sheet of paper.