anyone意为任何一个人,多用于否定句或疑问句,也可用于某些肯定句
Is anyone here?有人吗?Anyone can do it.随便谁都会.
something 有些/某人/某事,一般用于肯定句中
例：There is something wrong with you.(固定词组)
anything 意思是：1）有些,相对于something,用于疑问句中；2）任何事
用法：1.(用于疑问句或if从句时)什么东西,什么事情
Do you have anything to say?
2.(用于否定句时)任何东西,任何事情
Don't be dependent on anyone for anything.
3.(用于肯定句时)无论什么东西,无论什么事情
My dog will eat almost anything.
everything 意思是：每一件事
用法：Everything is ready.（万事俱备）
She does everything to help her mother.她尽全力帮助她母亲.