在操场上的英文是：on the playground
在操场上十 in ten playground
在操场上- On the Playground
在操场上玩 Playing in the playground ; Play in the playground
站在操场上 Standing On The Playground
就在操场上 Just On The Playground
在操场上跑步 run on the playground
位置在操场上 on the playground
在大操场上玩 Playing in the playground ; Play in the big playground ; Large playground
学生们聚集在操场上观看演出。
Students gathered on the playground to watch the performance.
在操场上和校园里，你都可以看到MS-13的成员挥舞着蓝白色旗子招募新成员。
At playgrounds and schoolyards, you can see MS-13 members flashing their blue-and-white colors, looking for new recruits.
article.yeeyan.org
要是看到哪个老师在操场上和孩子们聊天，他会因为愿意主动与学生建立课室外的联系而赢得同事们的尊重。
Colleagues seen chatting with kids in the playground are admired by their peers for going the extra mile to build on the more formal classroom relationship.
为什么不用on？？
追答也不是不行，但通常是在操场“里面”