Usput provjeri je li autobus već stigao.

On the way, check if the bus has already arrived.

Breakdown of Usput provjeri je li autobus već stigao.

• biti: to be
• autobus: bus
• stići: to arrive
• provjeriti: to check
• već: already
• li: whether
• usput: on the way

Questions & Answers about Usput provjeri je li autobus već stigao.

What does usput mean, and why is it at the beginning?

Usput literally means “along the way / in passing / while you’re at it.” Putting it first sets the “by the way” context for the whole sentence.
You can also move it: Provjeri usput je li autobus već stigao. The meaning stays similar; starting with Usput just sounds natural and frames it as an extra, quick task.

Why is provjeri used here? What form is it?

Provjeri is the imperative (command), 2nd person singular of provjeriti (to check). It’s telling one person informally: “Check …”
If you’re speaking formally to one person or to multiple people, you’d typically use provjerite.

Is there a difference between provjeri and something like provjeravaj?

Yes—this is about aspect.

• provjeri (from provjeriti, perfective) suggests one completed check: “check (once) and find out.”
• provjeravaj (from provjeravati, imperfective) suggests ongoing or repeated checking: “keep checking / check regularly.”
  In this sentence, a single check is what’s intended, so provjeri fits best.

How does je li work? Is it the same as da li?

je li is a common way to introduce a yes/no question in Croatian, especially in more standard style. It’s basically “is it that…?”

• je = the present form of biti (to be) used as an auxiliary here
• li = question particle
  da li can also introduce yes/no questions in many contexts, but je li is very common and often preferred in standard written Croatian. In speech, je li is often shortened to jel’.

Why is there a period, not a question mark, if there’s a question inside?

Because the main sentence is a command (Provjeri…), not a direct question to the listener. The question is embedded (indirect/embedded yes-no clause): check whether the bus has arrived.
So you normally end with a period: Usput provjeri je li autobus već stigao.
A question mark would be used if the whole sentence were a direct question.

What tense is stigao, and why is it stigao (not stigla or stigli)?

This is the past participle in the perfect construction: je … stigao = “has arrived.”
The participle agrees in gender and number with the subject autobus, which is masculine singular, so it’s stigao.
Examples:

• autobus je stigao (masc. sg.)
• autobusna linija je stigla (fem. sg.)
• autobusi su stigli (masc. pl.)

Why is autobus in the basic form (nominative)? Shouldn’t it be in another case?

No—because autobus is the subject of the embedded clause je li autobus već stigao (“whether the bus has arrived”). Subjects are in the nominative.
If you were saying “check the bus” as an object, then you’d likely use an object case, e.g. Provjeri autobus (accusative) meaning “inspect/check the bus” (a different meaning).

What does već do here, and is its position fixed?

već means “already.” It modifies the timing of the arrival: already arrived.
Its position is fairly flexible, but it most naturally appears before the verb/participle phrase:

• je li autobus već stigao (very natural)
  You could also hear variations depending on emphasis, but the given placement is standard.

Could the word order be je li autobus stigao već or je li već autobus stigao?

Croatian word order is flexible, but different orders sound more or less natural and can shift emphasis:

• je li autobus već stigao = neutral/most common
• je li već autobus stigao = more emphasis on already (like “has the bus already arrived?”)
• je li autobus stigao već = possible, but often sounds more marked or context-dependent

Is je li always required, or can you form the embedded question differently?

You can also embed the yes/no question in other ways, depending on style:

• Provjeri je li autobus već stigao. (very common)
• Provjeri da li je autobus već stigao. (also common in many regions/styles)
  You can’t just use a direct-question structure with a question mark here if you want it to stay an embedded clause; the main verb provjeri sets it up as “check whether…”.