他总是自己一个人在河边或草地等地方踢足球

He is always playing football on the river or grassland and other places alone.

he is always playing football by the river or on the grass on his own

He always play football somewhere by the river or grass by himself.
有不明白的地方再问哟,祝你学习进步,更上一层楼! (*^__^*)