钢铁 (gāng tiě): steel

This large bridge is built with steel, so it is very sturdy and can bear the weight of heavy trucks.

During wartime, steel was an important material for making weapons and tanks, and it was very precious to the country.

He persisted in exercising every day and developed an iron will, able to overcome even the greatest difficulties.

The workers at this steel plant are busy day and night, smelting iron ore into high-quality steel to supply automobile manufacturing plants.

After ten years of effort, this company finally became a leading enterprise in the steel industry.