我发现有一个人正躺在街上（英文翻译）

I found a man lying in the street

I saw that there is a man lying on the street

I found a man lying on the steet.

I realized that there is a person lying on the street

I found a man lying in the street.
find sb. + n. + Ving形式
发现某人做某事,固定搭配
see sb doing sth. 看见某人正在做事,在这里并不合适.

i find that there is a man lying on the stree
i saw a man lying on the stree