北美洲紫燕

例句：

1. 1.The swallows are known for their distinctive calls.
   燕子以其独特的叫声而闻名。
2. 2.The migration patterns of swallows are fascinating to study.
   燕子的迁徙模式令人着迷，值得研究。
3. 3. The swallows are a symbol of spring in the North American region.
   燕子是北美地区春天的象征。