La sidinta gasto nun staras ĉe la pordo.

Because -inta shows an action or state that happened before the main verb.

• sidanta = sitting, currently in the state of sitting
• sidinta = having sat / having been sitting, earlier

In the sentence:

La sidinta gasto nun staras ĉe la pordo.

the guest is standing now, so they are not sitting now. sidinta tells you that the sitting came first, and the standing is the current action.

A fuller version would be something like:

La gasto, kiu sidis, nun staras ĉe la pordo.
= The guest, who was sitting, is now standing at the door.

It is made from:

• sidi = to sit, to be sitting
• -int- = active past participle marker
• -a = adjective ending

So:

sidi + int + a = sidinta

Because it ends in -a, it works like an adjective and describes gasto.

Because it is acting as an adjective modifying gasto.

In Esperanto, adjectives end in -a, and they agree with the noun they describe.

So:

• gasto = guest
• sidinta gasto = a guest who had been sitting

If the noun were plural, the adjective would also become plural:

• la sidintaj gastoj = the guests who had been sitting

Because neither word is a direct object here.

• gasto is the subject of staras
• ĉe la pordo is a prepositional phrase, and prepositions normally do not take -n

So:

• La sidinta gasto = the sitting/formerly sitting guest → subject
• ĉe la pordo = at the door

You would use -n only for a direct object, or sometimes for motion toward something in special cases, but not here.

ĉe usually means at, by, with, or in the vicinity of, depending on context.

Here, ĉe la pordo means:

• at the door
• by the door

It suggests location near the door, not movement toward it.

This is different from, for example:

• al la pordo = to the door
• apud la pordo = beside the door

In this sentence, ĉe is a natural choice for someone standing at the door.

Nun means now, and it is an adverb. Esperanto word order is fairly flexible, but this placement is very natural.

So:

La sidinta gasto nun staras ĉe la pordo.

emphasizes the contrast in time:

• earlier: the guest was sitting
• now: the guest is standing

You could also say:

La sidinta gasto staras nun ĉe la pordo.

but the original sounds more natural in most contexts.

Because staras is simpler and more idiomatic.

• staras = is standing
• estas staranta = is in a standing state

Both are possible, but Esperanto often prefers the simple verb when it already expresses the idea clearly.

So:

nun staras is the normal, natural way to say is now standing.

Not exactly. Seated guest in English usually describes the guest’s current position. But sidinta gasto means the guest had been sitting before.

So the sense is closer to:

• the guest who had been sitting
• the formerly seated guest
• the guest who was sitting

Because the sentence continues with nun staras, the time contrast is important.

If you wanted to describe a guest who is seated right now, you would normally use:

sidanta gasto = a guest who is sitting

La is the definite article, meaning the.

• La sidinta gasto = a specific guest already known from context
• la pordo = a specific door, also known or understood from context

Esperanto uses la much like English the.

So this sentence is not about just any guest and any door, but about a particular guest and a particular door.

Yes. Sidinta is an active past participle used adjectivally.

Esperanto participles are very systematic. For active participles:

• -anta = doing, ongoing
• -inta = having done, earlier
• -onta = about to do, later

From sidi:

• sidanta = sitting
• sidinta = having sat / having been sitting
• sidonta = about to sit

In this sentence, the participle works like a shortened relative clause:

• la sidinta gasto
• = the guest who had been sitting

Yes. A very clear equivalent is:

La gasto, kiu sidis, nun staras ĉe la pordo.

This means essentially the same thing:

• kiu sidis = who was sitting

The participle version is more compact:

• la sidinta gasto

Learners often find the relative clause easier at first, but Esperanto uses participles very productively, so it is worth getting used to them.

Yes. Sidi means to be sitting, not to sit down.

This is an important distinction in Esperanto:

• sidi = be in a sitting position
• sidiĝi = sit down, become seated

So sidinta comes from sidi, meaning the person was in the seated state earlier.

That fits the sentence well:

• earlier: the guest was sitting
• now: the guest is standing

Yes, to some extent. Esperanto word order is flexible as long as the grammar stays clear.

For example, you could say:

• Nun la sidinta gasto staras ĉe la pordo.
• Ĉe la pordo nun staras la sidinta gasto.

These versions shift emphasis:

• starting with nun emphasizes time
• starting with ĉe la pordo emphasizes location

But the original order is straightforward and natural:

La sidinta gasto nun staras ĉe la pordo.