brown spot of apple

例句：

1. 1.The apple is slightly brown on the side.
   这个苹果侧面有点褐色。
2. 2. There's a brown spot on the tablecloth.
   桌布上有一块褐色的污渍。
3. 3. The apples are starting to turn brown as they ripen.
   随着苹果成熟，它们开始变褐。