they are having a good time on the playground .they ----- --

同学,很高兴回答你的问题
正确答案：填 are having fun 或 are enjoying themselves
即：They are having fun on the playground.
或：They are enjoying themselves on the playground.
翻译：他们在操场上玩得很开心.
解析：have a good time = have fun = enjoy oneself 玩得开心,过得愉快
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