jack ladder

例句：

1. 1. The jackladder was used to lift heavy objectsup and down the stairs.
   梯子被用来把重物上下楼梯。
2. 2. Theworkers used the jackladder to reach high shelves inthe store.
   工人们使用梯子到达商店高处的货架。
3. 3. The jack ladderwas a useful tool for moving heavy furniturearound the house.
   梯子是搬运家具在房子周围移动的一种有用的工具。