steel for special purposes

例句：

1. 1. The construction of the bridge required a large amount of steel.
   建造这座桥需要大量的钢材。
2. 2. Steel is stronger than wood and can be used for various purposes.
   钢比木头更坚固，可以用于各种用途。
3. 3. Steel is often used in the production of tools and machinery.
   钢通常用于生产工具和机械。