a grave error(= a very serious mistake)

• 严重错误

a grave error(= a very serious mistake)的用法和样例：

例句

1. He hasn't made any serious mistakes that I know of.
   根据我所知，他没犯过什么严重错误。
2. Though he had made a serious mistake, they did not punish him, out of consideration for his youth.
   尽管他犯了严重错误，他们考虑到他还年轻，并没有处罚他。