Hello! Is he looking for some juice. This sentence is correct because juice is an uncountable noun. That means it cannot be changed to plural, but is always called "juice" and not called "juices". The rules you quoted are correct, but it is important to also take into account countable and uncountable nouns. A similar example with countable nouns that can have both a plural "s" ending form, and regular single form is... "Does he want any books?" Singular... "Does he want a book?" or "Does he want any friends?" Singular... "Does he want a friend?" If we were to say "Does he want some friends" it make sense but sounds rather unnatural and if it were used would specifically imply that you know several friends that he would definitely get on with. Good job noticing a small difference in English usage and wanting to know how to use each sentence clearly! By the way, at least in American English, instead of saying "let me know if it's a trifle" we might say "Let me know if it is not important." We do sometimes use the word trifles here in the US, though. Such as in the following sentences. "Don't worry about such trifles." (Don't worry about such small unimportant things.) "He is always complaining about trifling matters." (He is always complaining about small and irrelevant things.) As you can see, this can be a noun, "trifles", or an adjective, "trifling". Neither words are used very often but when they are, they are used to describe a very insignificant and pointless matter, especially in a negative sense. Good job in your study of English and feel free to message me directly if you have any other questions! : )

I hope this helps.. Some 1. Some is used with both countable and uncountable nouns: Ex: Countable Nouns - 'Some people in my school like Jazz.' Uncountable Nouns - 'There was some snow here last winter.' 2.Positive sentences Some is used in positive sentences: Ex: 'I have some friends.' 'We bought some coffee.' 3. Offering We use some in questions when we expect the answer to be 'yes' or when we are offering something, otherwise, we use any: Ex: 'Would you like some milk? 4. Requests Some is also used in questions when we are making a request: 'Can I borrow some money?' Any 1. Negative sentences Any is used in negative sentences: 'I don't have any friends.' 'There isn't any bread left.' 2. Questions Any is used in questions: Ex: 'Do you have any money?' 'Is there any sugar?' You may send me a message for further questions. I'd be glad to help.

In this case, I think "some juice" and simply "juice" would be semantically equivalent. I don't sense much difference between these: Is he looking for juice? Is he looking for some juice? If a linguist insisted, I'd explain the difference similar to how you did with one correction. Compare these two questions: 1. Is someone there? 2. Is anyone there? Like you say, in 1 the "some" anticipates an affirmative answer. You more than 50% expect the answer to be yes. The correction I'd make to your explanation is that you *expect* the answer to be yes, but you don't necessarily *want* it to be yes. In 2, you would more than 50% be expecting the answer to be no, even if you wanted it to be yes. If the textbook is presenting that sentence as an example of the some/any opposition, the unmodified equivalent (Is he looking for juice?) would be the more uncertain version. Having said all that, yeah, I think other native speakers wouldn't put this much thought into it, and they would or wouldn't use "some" interchangeably in this case.