stack pop-up

例句：

1. 1. The boxes are stacked neatly on the shelves.
   箱子整齐地堆放在架子上。
2. 2. He stacked the books on the desk.
   他把书堆在桌子上。
3. 3. The workers stacked the crates in the warehouse.
   工人们把箱子堆在仓库里。