他看见他的同学在操场踢足球，也加入进去了。
He saw his classmates playing football on the playground and joined them.
他们准是在操场上踢足球，是不是？
They must be playing football on the sports ground, aren't they?
有一天，我在操场上跟同学踢足球的时候摔倒了，腿伤的很严重。
One day, while I was playing football with my classmates on the playground, I fell down and hurt my legs badly.
我们在操场上看男孩子们踢足球。
我们在操场上看男孩子们踢足球。
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