Questions & Answers about Jedeš li sir i kruh?
Why don't sir and kruh have special endings since they are the objects being eaten?
This is the special rule for inanimate masculine nouns! In the accusative case (when a word is the direct object of the verb), masculine nouns for non-living things like sir (cheese) and kruh (bread) stay exactly the same as their dictionary form. If they were living things, they would get an -a ending instead.
How does li work to form a question here?
The word li is a little particle used to ask yes/no questions. To make this kind of question, you take the main verb, put it at the very beginning of the sentence (Jedeš), and immediately follow it with li.
Why isn't the word ti (you) in this sentence?
In Croatian, the verb ending tells you who is doing the action. The -š at the end of Jedeš already means "you" (singular) are doing it. Because of this, pronouns like ti are usually dropped unless you really want to emphasize who is eating.
Does Jedeš mean "you eat" or "you are eating"?
It means both! Croatian only has one present tense. Depending on the context, Jedeš li sir i kruh? can mean "Do you eat cheese and bread?" (as a general habit) or "Are you eating cheese and bread?" (right now).