Indonesian does not conjugate ter- verbs for tense, aspect, mood, or person. The predicate remains unchanged while separate preverbal particles supply meanings such as completion, continuation, prediction, possibility, and negation: sudah terbuka, akan terjatuh, tidak terbaca, belum terdengar.
The syntax is straightforward, but interpretation is not always mechanical. A result state behaves differently from a punctual accident, and ability-like terbaca interacts with bisa differently from ordinary action verbs. English speakers must therefore track both particle scope and the lexical aspect of the ter- predicate. The broader ordering system is mapped in the aspect and modality overview.
The stable predicate and its preverbal markers
The basic pattern is:
subject + negation/aspect/modal particles + ter- predicate + complements/adjuncts
| Function | Model | Core interpretation |
|---|---|---|
| completed transition / current result | Pintunya sudah terbuka | the open state has been reached |
| ongoing perception | Suaranya sedang terdengar | the sound is currently audible |
| prospective | Saya akan terjatuh | a fall is predicted, not intended |
| possibility | Saya bisa terjatuh | there is a risk that I will fall |
| plain negation | Tulisan itu tidak terbaca | the writing is illegible / cannot be made out |
| not-yet negation | Suaranya belum terdengar | the sound is not audible yet |
| preventive directive | Jangan sampai terjatuh | take care so that a fall does not occur |
Pintunya sudah terbuka sejak pukul tujuh.
The door has been open since seven.
Suaranya sedang terdengar putus-putus melalui sambungan telepon.
Her voice is currently coming through intermittently over the phone.
Kalau terus mundur, saya akan terjatuh.
If I keep backing up, I will fall.
Hati-hati, kamu bisa terjatuh dari tangga itu.
Be careful, you could fall from those stairs.
Nomor serinya tidak terbaca karena tintanya luntur.
The serial number is illegible because the ink has run.
Dari tadi namanya belum terdengar dipanggil.
Her name has not yet been heard being called.
None of the particles attaches to the verb. Sudahterbuka, akanterjatuh, and tidakterbaca are spelling errors. Conversely, the derivational prefix remains attached: terbuka, never ter buka.
Sudah: reaching or maintaining an endpoint
With a result state, sudah says that the transition into the state has occurred; context decides whether the state still holds. A duration phrase such as sejak pagi strongly favors a continuing-state interpretation.
Sebelum tamu pertama datang, pintunya sudah terbuka.
Before the first guest arrived, the door was already open.
Pintunya sudah terbuka selama dua jam.
The door has been open for two hours.
Pintunya sudah terbuka, lalu ditutup lagi oleh petugas.
The door was already open, and then the attendant closed it again.
With a punctual accidental event, sudah presents the endpoint as completed.
Saat saya menoleh, anak itu sudah terjatuh.
When I looked over, the child had already fallen.
Dua pengendara sudah terjatuh di tikungan itu pagi ini.
Two riders have already fallen at that bend this morning.
With perceptibility predicates, sudah often means “has become perceptible” after some threshold was crossed.
Setelah kontrasnya dinaikkan, tulisan itu sudah terbaca.
After the contrast was increased, the writing became legible.
Begitu pengeras suaranya dinyalakan, pengumuman itu sudah terdengar jelas.
As soon as the loudspeaker was switched on, the announcement could be heard clearly.
Indonesian sudah is not simply English present perfect have. It marks a relevant attained phase; English may translate it with “already,” “has become,” “had,” or a simple past depending on context.
Sedang: an ongoing phase, with lexical restrictions
Sedang selects a phase in progress. It combines most naturally with a sound that continues or with a state understood as temporarily holding.
Musik dari aula sedang terdengar sampai ke lobi.
The music from the hall can currently be heard as far as the lobby.
Pintu garasi sedang terbuka karena barang-barang sedang diturunkan.
The garage door is currently open because the goods are being unloaded.
The second clause distinguishes two aspectual structures. Sedang terbuka views an open state as temporarily holding; sedang dibuka views the opening action as unfolding.
Pintunya sedang terbuka.
The door is currently open.
Pintunya sedang dibuka oleh petugas.
The door is being opened by the attendant.
Punctual terjatuh has no long stable middle phase, so sedang terjatuh needs an unusual context: slow motion, an interrupted fall, or a viewpoint inside the event. For an ordinary report, use baru saja terjatuh or sudah terjatuh.
Dalam rekaman gerak lambat itu, tubuhnya terlihat sedang terjatuh ke samping.
In that slow-motion recording, his body can be seen falling sideways.
Seorang penonton baru saja terjatuh di dekat pintu keluar.
A spectator has just fallen near the exit.
This restriction comes from event shape, not from the prefix alone. Ongoing terdengar is natural because a sound can remain audible; ongoing terjatuh is marked because reaching the ground is a bounded endpoint.
Akan: prediction without intentional control
Akan places the state or event after the reference time. With ter-, it usually expresses a prediction, scheduled resultant state, or developing risk—not the subject's intention.
Setelah sistem diperbarui, menu baru akan terlihat di layar.
After the system is updated, a new menu will appear on the screen.
Pintunya akan terbuka otomatis saat kartu dipindai.
The door will open automatically when the card is scanned.
Tanpa pegangan, saya akan terjatuh.
Without something to hold on to, I will fall.
Because terjatuh presents low control, Saya akan terjatuh cannot normally mean “I intend to fall.” A planned action needs an agentive predicate.
Dalam adegan itu, saya akan menjatuhkan diri ke matras.
In that scene, I will throw myself onto the mat.
With negation, neutral order places tidak before akan:
Tanpa kunci akses, pintunya tidak akan terbuka.
Without an access key, the door will not open.
The marked order akan tidak terbuka can contrast a future non-open condition, especially in careful analytical prose, but it is not the default way to say “will not open.” Particle order follows scope, not English auxiliary movement.
Bisa: ability, possibility, and redundancy
With an involuntary event, bisa normally expresses circumstantial possibility or risk rather than a learned ability.
Kalau berdiri di kursi itu, kamu bisa terjatuh.
If you stand on that chair, you could fall.
Kotaknya bisa terbawa arus kalau tidak diikat.
The box could be carried away by the current if it is not tied down.
With perception predicates, bisa may emphasize that conditions permit the result.
Dengan lampu tambahan, tulisan itu bisa terbaca dari belakang.
With additional lighting, the writing can be read from the back.
Kalau mikrofon didekatkan, suaranya bisa terdengar lebih jelas.
If the microphone is moved closer, her voice can be heard more clearly.
Because negative terbaca already has a conventional “legible/readable” interpretation, extra bisa may be semantically heavy but is not automatically ungrammatical. Choose according to scope and emphasis:
Nomornya tidak terbaca.
The number is illegible.
Nomornya tidak bisa terbaca oleh pemindai lama itu.
The number cannot be read by that old scanner.
Dengan kualitas cetak serendah ini, sebagian angka bisa tidak terbaca.
With print quality this poor, some digits may be illegible.
Tidak bisa terbaca negates the possibility of a readable result. Bisa tidak terbaca asserts the possibility of a nonreadable result: “may fail to be legible.” The difference comes entirely from particle order.
Tidak and belum: two kinds of negation
Use tidak for a plain negative predicate. Use belum when the expected or relevant endpoint has not been reached yet.
Pintunya tidak terbuka meskipun kartunya sudah dipindai.
The door did not open even though the card had been scanned.
Pintunya belum terbuka; acaranya baru dimulai pukul sembilan.
The door is not open yet; the event does not start until nine.
Nama pemenangnya tidak terdengar karena sambungannya putus.
The winner's name could not be heard because the connection dropped.
Nama pemenangnya belum terdengar; pembawa acara masih membuka amplop.
The winner's name has not been heard yet; the host is still opening the envelope.
With terjatuh, belum can sound ominous because it frames falling as an anticipated endpoint:
Motornya oleng, tetapi pengendaranya belum terjatuh.
The motorcycle is wobbling, but the rider has not fallen yet.
Compare sudah tidak and belum:
Setelah pintunya ditutup, musiknya sudah tidak terdengar.
After the door was closed, the music could no longer be heard.
Sebelum konser dimulai, musiknya belum terdengar.
Before the concert started, the music could not yet be heard.
Sudah tidak terdengar means an earlier audible phase has ended; belum terdengar says the audible phase has not begun. English often uses “not” for both, so this aspectual contrast deserves deliberate practice.
The negative belum terbaca is contextually ambiguous between a state and a reading event. An explicit cause or actor resolves it.
Tulisannya belum terbaca karena layar masih gelap.
The writing is not legible yet because the screen is still dark.
Pesan itu belum terbaca oleh petugas jaga karena baru saja masuk.
That message has not yet been read by the duty officer because it has just arrived.
Jangan: preventing an uncontrolled outcome
Jangan normally prohibits a controllable action. An accidental fall is not something a person can directly decide not to perform, so Indonesian often inserts sampai to frame the directive as prevention: do not let the unwanted endpoint be reached.
Pegang pegangannya agar jangan sampai terjatuh.
Hold the handrail so that you do not fall.
Jangan sampai pintunya terbuka saat kereta berjalan.
Do not let the door open while the train is moving.
Simpan salinannya agar data penting jangan sampai terhapus.
Keep a backup so that important data does not get deleted.
For a maintained state, an analytic causative with biarkan is often clearer than commanding the inanimate theme:
Jangan biarkan pintunya terbuka semalaman.
Do not leave the door open all night.
Casual warnings such as Jangan jatuh! “Don't fall!” are natural (informal) speech acts. They are preventive warnings, not evidence that falling has become a controlled action.
Why bukan is normally wrong here
Terbuka, terjatuh, terbaca, and terdengar function as predicates, so their ordinary negator is tidak, not bukan. Bukan negates or contrasts a nominal identification and can appear in a cleft around the clause.
Pintunya tidak terbuka.
The door is not open.
Bukan pintunya yang terbuka, melainkan jendelanya.
It is not the door that is open, but the window.
Bukan suaranya yang terdengar tadi.
It was not her voice that was heard earlier.
The second and third examples do not use bukan as a verbal negator. They contrast the focused noun phrase selected by yang.
Common Mistakes
1. Moving the marker after the predicate
❌ Tulisan itu terbaca tidak dari sini.
Incorrect neutral order—tidak belongs before the predicate.
✅ Tulisan itu tidak terbaca dari sini.
That writing is not legible from here.
2. Attaching a separate particle
❌ Pintunya sudahterbuka sejak pagi.
Incorrect spelling—sudah is a separate aspect particle.
✅ Pintunya sudah terbuka sejak pagi.
The door has been open since this morning.
3. Using bukan for predicate negation
❌ Suaranya bukan terdengar dari belakang.
Incorrect for plain negation—bukan does not normally negate this predicate.
✅ Suaranya tidak terdengar dari area parkir.
Her voice cannot be heard from the parking area.
4. Confusing an ongoing state with an ongoing action
❌ Pintunya sedang terbuka oleh teknisi.
Incorrect for an opening in progress—terbuka presents the state, and the agent phrase clashes with that reading.
✅ Pintunya sedang dibuka oleh teknisi.
The door is being opened by the technician.
5. Translating English “have not” word for word
❌ Saya tidak sudah terjatuh, tetapi jalannya masih licin.
Incorrect marker combination for ‘have not fallen yet.’
✅ Saya belum terjatuh, tetapi jalannya masih licin.
I have not fallen, but the road is still slippery.
Key Takeaways
- Keep the ter- predicate unchanged and place aspect, modal, and negative particles separately before it.
- Sudah marks an attained phase, sedang selects an ongoing phase, and akan projects the state or event forward.
- With terjatuh, akan and bisa usually express prediction or risk, not intention or learned ability.
- Tidak gives plain negation; belum means that a relevant endpoint has not been reached yet; sudah tidak means an earlier phase has ended.
- Particle order creates scope: tidak bisa terbaca and bisa tidak terbaca make different claims.
- Use jangan sampai to prevent an uncontrolled outcome and tidak, not bukan, for ordinary predicate negation.
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