leaf of Descartes

例句：

1. 1. The tree has many leaves that turn colors in the fall.
   这棵树有很多叶子，秋天时颜色会变。
2. 2. She picked up a leaf and examined it closely.
   她捡起一片叶子，仔细地观察起来。
3. 3. The scientist collected leaves from different parts of the forest for analysis.
   科学家从森林的不同地方收集了叶子进行分析。