stack cross section

例句：

1. 1. The boxes are stacked neatly on the shelf.
   盒子整齐地堆放在架子上。
2. 2. The workers were stacking the crates in the warehouse.
   工人们正在仓库里堆放箱子。
3. 3. The books are stacked in the library.
   书籍被整齐地堆放在图书馆里。