八角形

例句：

1. 1. The oak tree is the largest in the forest.
   橡树是森林里最大的树。
2. 2. They gathered acorns to make a fire.
   他们收集橡子来生火。
3. 3. The acorns are small and round, like nuts.
   橡子小而圆，像坚果一样。