这次旅行是一次很棒的经历。

This trip was a great ___experience.

我在牙医那里有一次非常不愉快的经历。

I had a very unpleasant ___experience at the dentist.

他的日本之行是一次他永远不会忘记的经历。

His trip to Japan was an ___experience he'll never forget.