a chain of undulating hills

例句：

1. 1. The chain of hills is a popular hiking trail.
   这些丘陵是一条受欢迎的徒步旅行路线。
2. 2. The undulating hills are a natural wonder that attracts many visitors.
   起伏的丘陵是一个自然奇观，吸引了许多游客。
3. 3. The hikers were amazed by the beauty of the chain of hills.
   登山者对连绵起伏的丘陵的美丽感到惊叹。