Koper besar itu dibawa ke hotel oleh petugas bagasi.

Because this sentence is in the passive voice.

• membawa = to carry / carries / carried in an active sentence
• dibawa = is carried / was carried in a passive sentence

Here, the sentence starts with Koper besar itu, so the suitcase is the main focus. Indonesian often uses di- passive when the thing affected by the action comes first.

Compare:

• Petugas bagasi membawa koper besar itu ke hotel.
  = The baggage staff carried that big suitcase to the hotel.

• Koper besar itu dibawa ke hotel oleh petugas bagasi.
  = That big suitcase was carried to the hotel by the baggage staff.

No. These are two different things:

• di- attached to a verb = a passive prefix
• di written separately before a noun = a preposition meaning in, at, on

So:

• dibawa = di-
  • bawa
    passive verb: be carried
• di hotel = at the hotel

A very common learner mistake is confusing these because they look the same in writing. A useful rule:

• If it is attached to a verb, it is usually the passive prefix.
• If it is written separately before a place noun, it is the preposition.

In your sentence, dibawa is definitely the passive verb.

Because Indonesian noun phrases usually follow this order:

noun + adjective + demonstrative

So:

• koper = suitcase
• besar = big
• itu = that

Together: koper besar itu = that big suitcase

This is normal Indonesian word order.

A useful contrast:

• koper besar itu = that big suitcase
• koper itu besar = that suitcase is big

So when besar comes inside the noun phrase, it describes the noun. When it comes after koper itu, it can act more like the predicate.

Itu is a demonstrative, usually meaning that. In many contexts, it also helps make a noun phrase specific, somewhat like the in English.

So koper besar itu can be understood as:

• that big suitcase
• or, depending on context, the big suitcase

Indonesian does not have articles like a/an/the, so words like ini and itu, plus context, often help show whether something is specific.

Compare:

• koper besar = a big suitcase / big suitcases / the big suitcase, depending on context
• koper besar itu = that specific big suitcase

Because ke shows movement toward a destination, while di shows location.

• ke hotel = to the hotel
• di hotel = at the hotel

Since the suitcase is being carried to the hotel, ke is the correct choice.

Compare:

• Koper itu dibawa ke hotel.
  = The suitcase was carried to the hotel.

• Koper itu ada di hotel.
  = The suitcase is at the hotel.

Oleh means by and marks the agent in a passive sentence, meaning the person or thing that performs the action.

So:

• oleh petugas bagasi = by the baggage staff

It is not always required in Indonesian. Often, the agent can appear without oleh, especially when it comes right after the passive verb.

For example:

• Koper besar itu dibawa petugas bagasi ke hotel.

That is also possible.

However, in your sentence, oleh is very helpful because ke hotel comes before the agent. It makes the structure clearer:

• dibawa ke hotel oleh petugas bagasi

Without oleh, the sentence could sound less clear or less natural in that order.

In this passive sentence:

• Koper besar itu is the grammatical subject/topic
• petugas bagasi is the doer/agent

So even though the baggage staff performs the action, the sentence is built around the suitcase.

That is one of the main functions of the passive in Indonesian: it lets the speaker put the affected thing first.

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

So dibawa does not automatically mean only was carried. Depending on context, it could be understood as:

• is carried
• was carried
• has been carried

English translations often choose the past passive, but Indonesian itself usually relies on:

• context
• time words such as kemarin (yesterday), tadi (earlier), besok (tomorrow)
• the surrounding conversation

So if this sentence appeared alone, tense would be inferred from context.

Literally:

• petugas = officer, staff member, attendant, personnel
• bagasi = baggage, luggage

So petugas bagasi means something like:

• baggage staff
• baggage handler
• luggage attendant
• sometimes porter, depending on context

The most natural English translation depends on the situation, but in Indonesian this is a normal noun phrase meaning staff responsible for luggage.

Because Indonesian does not have articles like English a/an/the.

Instead, Indonesian shows definiteness or specificity through:

• context
• demonstratives like ini and itu
• sometimes word order or other markers

In your sentence, itu helps make koper besar specific, so koper besar itu feels like that big suitcase or the big suitcase.

If you removed itu, the phrase would be less specifically identified:

• Koper besar dibawa ke hotel...

That could still be grammatical in the right context, but it would not point to a clearly identified suitcase in the same way.

Yes. Indonesian passive sentences often omit the agent when it is unknown, obvious, or unimportant.

So you could say:

• Koper besar itu dibawa ke hotel.

This means:

• That big suitcase was carried to the hotel.

This is very natural if the speaker cares more about what happened to the suitcase than about who carried it.

In fact, agent omission is one reason passive sentences are so common in Indonesian.