Dokter mengubah dosis obat.

Ubah is the basic root, meaning change.
Mengubah is the usual active verb form built from that root.

In Indonesian, many verbs take a meN- prefix when the subject is actively doing something to an object. Here:

• ubah = change
• mengubah = to change, change something

Because the sentence has a subject doing an action to an object:

• Dokter = subject
• mengubah = active verb
• dosis obat = object

So mengubah is the natural form here.

The prefix meng- is one form of the meN- prefix. It commonly marks an active transitive verb, meaning the subject performs an action on something.

So in this sentence, the doctor is acting on dosis obat.

A useful learner shortcut is:

• meN- + root often means to do that action to something

Examples:

• membaca buku = read a book
• menulis surat = write a letter
• mengubah dosis obat = change the medicine dose

The exact shape of meN- changes depending on the first sound of the root, so you may see forms like mem-, men-, meng-, meny-.

In Indonesian, the main noun usually comes first, and the word after it modifies it.

So:

• dosis obat = dose of medicine / medicine dose

The head noun is dosis, and obat tells you what kind of dose it is.

This noun order is very common in Indonesian:

• rumah sakit = hospital
• air minum = drinking water
• harga tiket = ticket price

So dosis obat follows a normal Indonesian pattern.

It can often be understood either way, depending on context.

• dosis usually corresponds to dose or dosage
• In a medical context, English may naturally say the medication dose, the drug dosage, or the dosage of the medicine

Indonesian often does not force the same distinction as English does. Context tells you whether it is a single dose, a general dosage level, or a prescribed amount.

Indonesian does not normally use articles like the, a, or an.

So:

• dokter can mean a doctor or the doctor
• dosis obat can mean a medicine dose, the medicine dose, or medicine dosage

Which one sounds best in English depends on context, but Indonesian usually leaves that unstated unless it needs to be made specific in some other way.

You usually know from context.

By itself, dokter can be:

• a doctor
• the doctor

It does not normally mean plural unless the context clearly suggests plural.

If Indonesian wants to make plural explicit, it might use:

• dokter-dokter = doctors
• para dokter = the doctors / doctors

So in this sentence, dokter is most naturally understood as a doctor or the doctor, depending on context.

Yes, it is a basic Subject–Verb–Object sentence:

• Dokter = subject
• mengubah = verb
• dosis obat = object

So the structure matches English quite closely:

• Doctor changed medicine dosage

This makes the sentence relatively straightforward for English speakers.

Indonesian verbs do not change form for tense the way English verbs do.

So mengubah by itself does not tell you whether the action is:

• present
• past
• future

Time is usually understood from:

1. context
2. time words

Examples:

• Dokter sedang mengubah dosis obat. = The doctor is changing the dosage.
• Dokter sudah mengubah dosis obat. = The doctor has changed / changed the dosage.
• Dokter akan mengubah dosis obat. = The doctor will change the dosage.

Without extra context, mengubah is just the general verb form.

Yes. Indonesian uses the passive very often.

A passive version would be:

• Dosis obat diubah dokter.
• Dosis obat diubah oleh dokter.

Here:

• diubah = is changed / was changed
• oleh = by

The version without oleh is also common, especially when the agent is already clear.

So:

• Dokter mengubah dosis obat. = active
• Dosis obat diubah (oleh) dokter. = passive

Obat most commonly means medicine, medication, or drug.

In some contexts, it can also mean remedy or cure, depending on what kind of treatment is being discussed.

So in dosis obat, it clearly refers to medicine or medication.

A simple learner-friendly approximation is:

• mengubah ≈ muhng-OO-bah

A slightly more careful breakdown:

• meng- sounds like məng with the ng sound from sing
• u is like oo
• bah has a clear a like in father

So:

• mengubah ≈ məng-oo-bah

The stress in Indonesian is usually not as strong or dramatic as in English.

In standard Indonesian, Dokter mengubah dosis obat is the better form.

Leaving off the prefix and saying ubah can happen in:

• casual speech
• headlines
• commands
• very informal styles

But for normal standard sentence-building, especially for learners, use mengubah here.

So:

• Dokter mengubah dosis obat. = standard
• Dokter ubah dosis obat. = possible in informal contexts, but not the best default form for learners