Definition
To be something that causes great excitement or interest for a brief period, but is quickly forgotten afterwards.
曇花一现
The new restaurant caused a great sensation when it first opened, but it quickly became a nine days' wonder.
那家新餐厅刚开业时引起了极大的轰动，但很快就成了昙花一现。
That app was a huge hit for a while after its launch, but now hardly anyone uses it. It was truly a nine days' wonder.
那个应用程序在推出后一度非常受欢迎，但现在几乎没人使用了。它确实是昙花一现。
His amazing performance was a nine days' wonder, and now everyone has forgotten about it.
他的精彩表演是昙花一现，现在大家都已经忘记了。