Omitted subject/object? plus some more questions.

[marte]

Na'vi strikes me as the sort of language that would omit subject/object when logic would permit it. But I haven't had the chance to pay proper attention to the few lines in Na'vi from the movie, so I can't really say.
Example:

Tsun nga-ri po-ti tse'a srak? (Can you see him/her?)

If you wanted to say something more than yes/no, which answer would be best?:
Tsun oe-ri po-ti tse'a. (I can see him/her.)
or
Tsun tse'a. (Can see.)

Or something else entirely? Even if there's no definite answer for this, do you reckon it's plausible enough?

Also, my knowledge of Na'vi grammar, especially syntax is very limited. I would appreciate any corrections to the sentences I used as examples to try and get my point across. I tend to stick to the (subject) (object) (verb) sentence order since it's what makes most sense to me. If you have any other particular order which seems to be used more frequently or makes more sense to you even if it's not officially accepted as the best, please share it. This is what interests me the most in Na'vi right now.

edit: although I used -ri here out of habit from Japanese, perhaps I should have used -l? How do I know when to use one or the other?

[omängum fra'uti]

You're not the only one to go with -ri as the preferred ending.  Yes, -l would be the correct one for typical sentences.

The -ri ending is giving a topic/context for the sentence (That's my understanding anyway) while the -l is giving the subject for the verb.  Just don't go crazy with -l...  The subject of an intransitive verb has no suffix, so if you try to say "I move" then Oe-l rikx would be most certainly incorrect, instead it should be Oe rikx.

[Skxawng]

Also keep in mind that while posting in the beginner forum, when adding suffixes, prefixes and infixes, remember to use the notation.

Tsun ngari poti tse'a srak? should be
Tsun nga-ri po-ti tse'a srak?

[omängum fra'uti]

Well technically it should probably be

Tsun nga-l po-ti tse'a srak?

To the original question, I don't have an answer, except to say in casual speech it is not uncommon in English and other languages for parts of a sentence to be dropped.  I would imagine the same goes with Na'vi.  What I could not answer is if that is acceptable in more formal speaking.

[marte]

I've edited my post accordingly. So sorry!

And thanks for your help, affixes are giving me a headache D:

[Brainiac]

It takes some getting used to.

what's a topic marker exactly, again?

[omängum fra'uti]

I'm not entirely sure, since English doesn't have one and I'm linguistically challenged.  But I believe it provides context for the rest of the sentence, while not actively participating.

In the plainest canon example I've seen, it's usage is easily taken to be a posessive suffix.  (1-TOP nose full, where 1-TOP provides context for who's nose it is.  It's the nose which is being full, not the speaker.)  However my feeling is it is much more than that, and it only seems like a posessive case because of that simple example.  I'm not sure what a topic would do to a sentence with a transitive verb or dative, for example.  However the grammar page does say that it "can also appear where a genitive or dative might be expected", as in the full nose where you would expect the genitive.

As an example of it replacing a dative...
Ay-tawtute-ru ayoeng-l fp<ay>e' 'upxare-ti
to-sky-people we will-send message

Ay-tawtute-ri ayoeng-l fp<ay>e' 'upxare-ti
As-for-sky-people, we will-send message

In both cases, it means the same thing.  "We will send the sky people a message."

(And no, I'm pretty sure neither of those are how they said it in the movie while translating Jake's inspirational rally.)

[marte]

I don't think "ri" can replace "ru" in that case. In my head, "ru" is a bit like a Japanese "ni" as "ri" is a "wa". If you send someone something, you would absolutely have to affix "ru" to the receiver.

As for -ri, it does exactly what its name says, marks a topic. But its usage in Na'vi is a bit different than most languages that use a topic marker, because there is also a subject marker (the subject of a sentence is usually the topic as well).
Per example, if you were going to say "I will go outside", you would use the topic marker after "I". But In Na'vi, you would use the -l marker instead.

[omängum fra'uti]

Na'vi is not Japanese though...  In Japanese as I understand it, there is nothing quite like the Na'vi -ri, because the topic marker is also the subject.  (Correct me if I'm wrong here, I don't know Japanese, just going on what I've seen people here say.)

But in Na'vi, the topic and the subject/object of the action are independent of each other.  What I said without the topic would just be "We send message", with it ambiguous who the message is going to.  But the topic gives a context without changing the action itself.  It's not applying a dative to "send" - send still just has a subject and object.  But when we apply the sky people as a topic, the action is taken within the context of the sky-people, so the ambiguity can be taken to mean it's a message for the sky people.

I think it was a direct quote from Dr. Frommer where I got the idea of using -ri to replace a dative.  (It was saying that -ri can sometimes be used in place of -ti or -ru).