The idea of "focus" is that in the subject and/or object positions of a sentence there must always be at least a main concept. The "focus" in the subject position is always the subject itself, and the "focus" in the object position we usually call the direct object in English grammar. That might sound complicated, but it boils down to the general rule that we use i/si/iya with the subjects and direct objects of a sentence. Here are some examples to help clarify:
- Dånkolo i gima'. = The house is big.
The subject in this case is the "house" so in Chamorro we precede it by the article i. There is no object in this sentence.
- Humånao i patgon. = The child went.
The subject in this sentence is "child" so we use the article i. Once again there is no object.
- Ha chule' i lepblo. = He took the book.
The subject here is unspecified and only a pronoun is used, so it doesn't need a marker. However, the object "book" does need one, so we use i.
- I taotao ha sangåni yo'. = The person told me.
The subject here is "person" so we use i, and the object is a pronoun so we do not need an article in Chamorro.
- I biha ha fa'nå'gue i patgon. = The old woman taught the child.
In this case we have "old woman" and "child" in the subject and object case, respectively, so we use the article i in both cases.
The above examples are relatively simple sentences in Chamorro, the the concept still holds in more complicated ones as well. Here are some examples with indirect objects thrown in.
- Lini'e' i patgon ni ma'estra. = The child was seen by the teacher.
In this the subject is the "child" so we use the article i. The "teacher" is more or less used as a modifier in this sentence, to help us understand how the child was seen. In Chamorro we would treat "teacher" as a non-focus of the sentence.
- I palao'an ha chule'guan i asagua-ña ni yabi-ña. = The lady (accidentally) took her husband's keys.
Here we have a subject and two objects. The subject is "lady" so we use i. The direct object of the verb "chule'guan" is the "husband," so use use "i" in front of "asagua-ña."
- I tata na sangåni i lahi-ña ni estoria. = The father told his son the story.
The "father" and "son" are subject and direct object, respectively, so we, therefore, use i in both cases. The "story" is an indirect object.
- Dånkolo si Juan. = John is big
The subject is "John," and since "John" is a proper name we use si.
- Humånao si Maria. = Maria went.
Once again the subjet is a proper name, so we use si.
- Dikike' na isla iya Guåhan. = Guam is a small island.
The subjet here is "Guam," the proper place name of the island, so we use iya rather than i or si.