Some and any are used when it is not easy or necessary to say exactly the number of something.
Some is for positive sentences. It is also used in questions when we want or think the answer will be yes.
Any is for negative sentences and for questions.
- I will buy some beer.
(positive sentence) - Could I have some beer, please?
(The speaker expects the listener to say yes.) - You never give me any beer.
(negative sentence) - Have you got any beer?
(question)
