v. become hard or harder
v. make hard or harder
vt. 使变硬, 使坚强, 使冷酷
vi. 变硬, 变冷酷
1. The cold weather will harden the clay.
寒冷的天气会让泥土变硬。
2. She needs to harden her resolve to achieve her goals.
她需要坚定决心才能实现自己的目标。
3. The metal will harden when it is cooled quickly.
金属在快速冷却时会变硬。