There are some people on the grass改为一般疑问句并作否定回答

改为一般疑问句：Are there any people on the grass?

否定回答:No,there aren’t 

解析：在英文中there be结构改为一般疑问句只需将be动词are提前，疑问句中some改为any，否定回答用there be的否定形式即可。