An unforgettable experience can be referred to as a "memorable moment" or "a time to remember". It is a personal event that has a significant impact on a person and leaves a lasting impression.
For example:
"My trip to Paris was an unforgettable experience. The beauty of the city and the rich culture left a lasting impression on me."
"The birth of my first child was an unforgettable experience. Holding her in my arms for the first time was a moment I will never forget."
中文翻译：
"我的巴黎之旅是一次难忘的经历。这座城市的美景和丰富的文化给我留下了深刻的印象。"
"生下我的第一个孩子是一次难忘的经历。第一次抱着她是我永远不会忘记的时刻。"