Determiners like some, any, each, every, either, neither, all, both, much, many and most can be used directly before nouns, without of.
- Have you got any sugar? (NOT Have you got any of sugar?)
- Most people like children. (NOT Most of people like children.)
But if we want to put one of these determiners with an article, a possessive or a demonstrative, we have to use of.
Compare:
- Some people want a new system. (NOT Some of people want a new system.)
- Some of these people want a new system. (NOT Some these people want a new system.)
- Each child needs education. (NOT Each of child needs education.)
- Each of my children was given a toy. (NOT Each my children was given a toy.)
- Neither answer is correct. (NOT Neither of answer is correct.)
- Neither of these answers is correct. (NOT Neither these answers is correct.)
Notes
The determiners no and every are not used before of. Instead we use none and everyone.
- He has no friends.
- None of his friends remembered his birthday. (NOT No of his friends remembered his birthday.)
- Every boy has handed in his work.
- Every one of the boys has handed in his work. (NOT Every of the boys has handed in his work.)