Hello, I have a question regarding usage of any. My question is, can I omit any in cases like the following? I have a grammar book named 'Practical English Usage' that says "With an uncountable or plural noun, 'any' usually suggests the idea of an indefinite but limited amount or number. When there is no idea of a limited quantity or number, we do not usually use 'any'. And It also says when our Interest is in knowing the the existense of something not knowing its amount or its number, we don't use 'any'. So what are the differences between my following sentences? Can I omit any?
1- Do you have any children/children? (can I omit 'any' here?"
2- I don't have any cars/cars. I go to college by bus.
3- Yesterday, I did not buy any flowers/flowers from the market.