a small nature的用法和样例：
- A small natural or artificial gem used as a bearing in a watch.
- A small natural depression that water drains into; a shallow gully.
- A small natural depression that water drains into;a shallow gully.
- There was a small natural meadow there, through which flowed a stream.
- A small adjustment will equalize the temperature in the two rooms.
- I hit on the book in a small book shop.