hard as nails的用法和樣例：
例句
- They are merciless, with hearts as hard as nails.
他們冷酷無情，鐵石心腸。 - Mrs. Macbeth has a heart as hard as flint.
麥克白夫人生來一副鐵石心腸。 - They are merciless, with hearts as hard as nails.
他們冷酷無情，鐵石心腸。 - He is as hard as flint where business is concerned.
他在生意上是冷酷無情的。
詞匯搭配
- as hard as nails 身體結實
