Learn Hardcore Indonesian: Dia mengetuk meja perlahan agar peserta tidak kaget. - He/She knocks on the table gently so that the participants are not startled.

dia = he or she (singular human). Gender is not specified.
It’s usually not used for “it.” For things, use demonstratives like itu/ini or the noun itself.
For respected people, use honorific beliau (formal/polite).

What’s the difference between dia and ia?

Both mean “he/she,” but:
- dia: neutral, works as subject or object, common in speech and writing.
- ia: more formal/literary; typically subject-only (e.g., Ia datang), not used after prepositions or as a direct object.
- Example: Saya melihat dia (I saw him/her); avoid Saya melihat ia.

Why is tidak used instead of bukan?

tidak negates verbs and adjectives: tidak kaget (not startled).
bukan negates nouns/pronouns: Dia bukan peserta (He/She is not a participant).
Since kaget functions as an adjective (“startled”), tidak is correct here.

What does agar do in this sentence?

How does agar compare to supaya and biar? Could I use untuk?

agar: slightly formal; common in writing/speeches.
supaya: neutral; very common in speech and writing.
biar: informal/colloquial.
untuk
- clause is not used with a finite subject; use it with a verb/noun phrase:
  - Natural: agar/supaya peserta tidak kaget.
  - Also OK: untuk mencegah peserta kaget (to prevent participants from being startled).
  - Avoid: untuk peserta tidak kaget (unidiomatic).

Is kaget the best word here? How does it differ from terkejut?

What does perlahan mean? Can it also mean “softly/gently,” or only “slowly”?

perlahan literally “slowly,” but with actions like knocking it implies doing it gently/softly.
Synonyms/variants:
- pelan (very common, neutral/informal)
- Reduplications: perlahan-lahan, pelan-pelan (more emphatic: very slowly/gently)

Where can I place perlahan in the sentence?

Flexible placement:
- Dia mengetuk meja perlahan agar ...
- Dia perlahan mengetuk meja agar ...
- Perlahan, dia mengetuk meja agar ...
- Dia mengetuk meja dengan perlahan agar ...
All are acceptable; the first is most common.

Why not say dengan perlahan instead of perlahan?

Both are fine. dengan perlahan is slightly more formal or explicit as an adverbial phrase. Plain perlahan is concise and very common.

What is the base form of mengetuk, and how is it built morphologically?

Base (root): ketuk “knock/tap.”
meN- prefix forms an active transitive verb; with roots starting in k, the k drops and the prefix surfaces as meng-:
- meN- + ketuk → meN(g)+etuk → mengetuk.
Related forms:
- ketukan (a knock; a beat in music)
- Reduplication for repeated knocking: mengetuk-ngetuk.

Can I just use the root ketuk (e.g., Dia ketuk meja)?

In standard Indonesian, mengetuk is preferred for a finite active verb.
Bare root ketuk appears in imperatives (Ketuk pintunya!) and is common in colloquial speech (Dia ketuk pintu), but it’s less formal.

Would memukul be okay instead of mengetuk?

memukul = to hit/strike (stronger force), not just a gentle tap. It would change the meaning. mengetuk is the natural choice for a soft tap/knock.

Is peserta singular or plural here? Do I need to mark plural with para?

Indonesian doesn’t mark number by default. peserta can mean “participant(s).”
To emphasize plural humans, add para: para peserta = the participants. Both forms are fine; use para if you want to be explicit.

Could I replace peserta with a pronoun like mereka?

Yes, if the participants have been mentioned: agar mereka tidak kaget = “so that they aren’t startled.”
Use peserta if introducing or highlighting their role (participants as a group in an event).

Is jangan possible instead of tidak (e.g., agar peserta jangan kaget)?

No. jangan is used for prohibitions/imperatives (“don’t ...”). In a purpose clause expressing a desired result/state, use tidak: agar peserta tidak kaget.