On my way home I saw some children were playing football in the street
问题描述：
On my way home I saw some children were playing football in the street
On my way home I saw some children _______ football in the street
同义句转换
答
playing
see 有两个搭配 see sb doing sth 和see sb do sth
可以这样记,前者是不常做的或是只看到过一次的,突然看到的,如你的例句；
后者是经常做的,比如“我天天看到他锻炼身体”
记住这个就行了,同类的词有很多