trapezoidal steel box girder

例句：

1. 1.The roof of the building is trapezoidal in shape.
   这座建筑的屋顶是多角形的。
2. 2. The carpenter used a trapezoidal board to make the table legs.
   木匠用一块多角形木板做桌子腿。
3. 3.The rectangular room was converted into a trapezoidal space for storage.
   将一个矩形房间改造成一个多角形储物空间。