rectangular beam

例句：

1. 1. The engineer used a rectangular beam to support the roof.
   工程师用一根矩形梁支撑屋顶。
2. 2.The construction crew used rectangular beams to build the new bridge.
   建筑工人使用矩形梁建造了新桥。
3. 3. The beam was too weak to hold the weight of the building.
   这根梁太弱，承受不住建筑物的重量。