桁等

例句：

1. 1. The bridge is made ofsteel girders and beams.
   这座桥由钢梁和钢柱建造。
2. 2. Theengineer used the wooden girder tosupport the weight of the building.
   工程师使用木梁来支撑建筑物的重量。
3. 3. The construction workerswere busy installing the steel girderson the new bridge.
   施工人员正在忙着安装新桥的钢梁。