sword of Damocles idiom
达摩克利斯剑（比喻随时可能发生的祸事）
If you have a sword of Damocles hanging over you/your head, something bad seems very likely to happen to you.
The threat of a cut in funding is hanging over the Opera House like a sword of Damocles. 政府威胁说要削减预算，这就好像是一把悬在歌剧院上方的达摩克利斯剑。