edge of the format

例句：

1. 1. The book has a red cover with a white edge.
   这本书封面是红色的，边缘是白色的。
2. 2. The mountain had a steep edge that made climbing difficult.
   这座山有一个陡峭的边缘，使得攀登变得困难。
3. 3. The artist used a brush to create the smooth edge of the painting.
   艺术家用刷子创造出画作的光滑边缘。