**Here are some examples of using the word «harden» in English:**
1. The cold weather has hardened the soil, making it difficult to dig.
2. After years of practice, his fingers have hardened and become calloused from playing the guitar.
3. The team's recent losses have hardened their resolve to win the next game.
4. She tried to harden her heart against his lies, but it was difficult to do.
5. The company's strict rules and regulations have hardened its image as a serious and professional organization.
6. The constant criticism from his boss has hardened his attitude towards work.
7. The soldiers' training has hardened them to the dangers of war.
8. The lack of sleep has hardened her eyes and made them look tired.
9. The wind and rain have hardened the wood, making it more durable.
10. The athlete's hard training and dedication have hardened his body and made him stronger.