stack capability

例句：

1. 1. The boxes were stacked neatly on the shelves.
   盒子整齐地堆放在架子上。
2. 2. She stacked the books in the corner of the room.
   她把书堆放在房间的角落里。
3. 3. The workers stacked the crates to make more space.
   工人们堆放箱子以腾出更多空间。