他是一个开心的男孩。

He is a happy boy.

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男孩子们在外面席地而坐，从他们发出的阵阵笑声来看，他们玩得很开心。

Outside the boys were sitting on the ground and, judging by the gales of laughter, they were having a ball.

《柯林斯英汉双解大词典》

我和一个叫本的男孩游地很开心，我们后来成了好朋友。

I swam happily with a boy called Ben and later we became good friends.

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