Learn Hardcore Indonesian: Jika kamu ragu, duduk diam sebentar lalu bertanya pada guru. - If you are unsure, sit quietly for a moment and then ask the teacher.

Both mean if. Jika is more formal and common in instructions or writing; kalau is neutral in everyday speech (often pronounced/spelled kalo). You could say:

Jika ragu, ... (formal/neutral)
Kalau kamu ragu, ... (natural in conversation) Very formal alternatives: apabila.

Why is there no “to be” in kamu ragu?

Indonesian usually drops a copula before adjectives and nouns. Kamu ragu literally “you doubtful” = “you are unsure.” You can add a verb for nuance:

Kamu merasa ragu = you feel unsure (emotional emphasis) Don’t use meragukan here; meragukan means “to doubt (something),” e.g., Saya meragukan jawabannya.

Is ragu the same as ragu-ragu?

Not exactly.

ragu = doubtful/unsure (about truth or correctness)
ragu-ragu = hesitant/indecisive (about acting) Both fit here, but ragu-ragu highlights hesitation to act: Kalau kamu ragu-ragu, ....

Can I drop kamu and just say Jika ragu?

Yes. Subject drop is common when context is clear: Jika ragu, .... For politeness, you could use Jika Anda ragu, ... (formal “you”). For plural “you,” use kalian.

What does duduk diam mean? Are both words verbs?

It’s a common collocation meaning “sit still/quietly.” Duduk = sit; diam = be still/silent. Together: “sit and be quiet.” Alternatives: duduk tenang, diam dulu. Don’t rearrange to duduk sebentar diam—that sounds odd.

Where does sebentar go, and what nuance does it add?

Sebentar (“for a moment”) usually follows the verb phrase: duduk diam sebentar. Variations:

sebentar saja (just a moment)
sejenak (a moment; slightly literary)
bentar (colloquial) You can also say sebentar dulu to mean “for a moment first.”

How does lalu work here? What about kemudian, terus, or dan?

Lalu links actions in sequence (“then/and then”): ... sebentar lalu bertanya .... Nuances:

kemudian = then/afterwards (a bit more formal)
terus = then/and then (casual, very common in speech)
dan = and (no inherent sequence) So: lalu/kemudian/terus are all fine; dan is weaker for “then.”

Why bertanya pada guru and not bertanya dengan guru?

With bertanya (“to ask”), the addressee is marked by kepada/pada/ke (or colloquially sama). Dengan means “with (together/using)” and is not used for the person you ask. So: bertanya pada/kepada/ke/sama guru, not dengan.

Which preposition is best: pada, kepada, ke, or sama?

Rule of thumb:

Formal: kepada guru
Neutral/formal: pada guru
Conversational: ke guru
Very informal: sama guru Many style guides prefer kepada for people, but pada is widely accepted.

What’s the difference between bertanya, tanya, and menanyakan?

bertanya (pada/kepada/ke/sama [person]) = to ask (intransitive); focus on the act and addressee. Example: Bertanya pada guru.
tanya = base verb; in speech you can use it like bertanya: tanya ke guru (casual).
menanyakan [thing] (kepada/pada [person]) = to ask about something (transitive, requires an object). Example: Tanyakan hal ini kepada guru. Using menanyakan without the “thing” sounds incomplete.

Should it be gurumu to mean “your teacher”?

Not required. Indonesian has no articles, so guru can mean “the teacher” from context. If you need to be explicit:

gurumu (your teacher; suffix -mu)
guru kamu (also fine) All of these work: bertanya pada guru / pada gurumu / pada guru kamu.

How can I make the imperative sound more polite?

Add -lah, or use softeners:

Duduklah diam sebentar, lalu bertanyalah kepada guru. (polite)
Silakan duduk diam sebentar, lalu tanya ke guru, ya. Other softeners: tolong, coba, sentence-final ya.

Is the comma after the conditional clause necessary?

Yes, it’s standard to put a comma after a fronted conditional: Jika (Kalau) kamu ragu, .... No comma is needed before lalu in a short sequence. You could add one after a long pause: ... duduk diam sebentar, lalu bertanya ..., but it’s optional here.

Any natural rephrasings with the same meaning?

Kalau kamu ragu, diam dulu sebentar, lalu tanya ke guru.
Jika ragu, duduklah sebentar, kemudian bertanya kepada guru.
Jika kamu ragu-ragu, duduk tenang dulu, kemudian tanyakan hal itu kepada guru. (uses tanyakan, so it explicitly mentions the “thing” being asked: hal itu)