flash in the pan 空欢喜一场，好景不长，昙花一现，神来之笔

【例句】
People will be looking in to see how good we are now and whether our success has just been a flash in the pan.

人们会来看看我们现在有多成功，看看我们的成功是否只是昙花一现。

Horowitz playing, we often have some unexpected flash in the pan.
霍洛维茨在演奏时，经常会有一些意想不到的神来之笔。