The carefree childhood became a thing of the past.

无忧无虑的童年已经是过去时了。

youdao

Through the song, let me feel once again as if a child who returns to the carefree childhood, so I love this song.

通过这首歌，让我仿佛又再一次回到了小时候那无忧无虑的童年时代，所以我很喜欢这首歌。

youdao

I was heartsick, for I felt that the splendid years of my carefree childhood had come to an end.

我很难过，因为我觉得我无忧无虑的美好童年生活结束了。

《柯林斯英汉双解大词典》

They can never grow up with the sweet naivety that makes childhood carefree.

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Apart from the work, Tsujihara had a relatively carefree childhood.

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