a bird of passage

例句：

1. 1. The bird of passage is a symbol of life's journey.
   过客是生命旅程的象征。
2. 2. She spent her childhood as a bird of passage between different countries.
   她童年时期在各国之间作为过客度过。
3. 3.During the migration season, many birds of passage gather in flocks to travel long distances.
   迁徙季节，许多过客聚集成群长途跋涉。