hard as nails
坚强无比；无情无心
口语·形容人坚强或冷酷
英文释义
tough, unfeeling, or unsympathetic
例句
My grandfather was hard as nails; he never showed emotion, even at funerals.
典故来源
源自19世纪英国，钉子象征坚硬，比喻人冷酷无情或身体极其强壮。