precast stair

例句：

1. 1. The architect designed the precast stair for the new building.
   建筑师为新建筑设计了预制楼梯。
2. 2.The construction crew used precast stair to quickly build the ramp.
   施工队使用预制楼梯快速搭建了斜坡。
3. 3. The precast stair was installed in the basement of the hospital.
   预制楼梯被安装在医院的地下室。