135-Some只能用于肯定句吗？

some只能用于肯定句吗？

I have some friends here. 

There is some water in the glass. 

He played some records for me.

There must be some mistakes.

表请求、建议等，期待肯定回答

Would you like some tea? 

Could you please give me some help? 

Are you waiting for some guests this morning? 

不受否定约束时 

Some students do not love physics. 

He hadn't seen her for some years.