tough steel

例句：

1. 1. The construction of the bridge required tough steel for its supports.
   建造这座桥需要用硬钢作为其支撑。
2. 2.The car's engine is made from high-strength steel to ensure durability.
   这辆车的发动机是用高强度钢材制造的，以确保耐用性。
3. 3. The engineer used tough steel to make the cutting tool more durable and efficient.
   工程师使用硬钢制作了这种切割工具，使其更耐用且高效。