rigid steel

例句：

1. 1.The construction of the bridge required a lot of rigid steel.
   建造这座桥需要大量的坚硬钢。
2. 2.The car is made of rigid steel and has a strong engine.
   这辆车是用坚硬钢制造的，发动机很强劲。
3. 3.The engineer used rigid steel to reinforce the structure.
   工程师用坚硬钢加固了结构。