Learn Hardcore Indonesian: Perawat membantu dokter di rumah sakit setiap pagi. - The nurse helps the doctor in the hospital every morning.

Indonesian does not use definite or indefinite articles (like the or a/an). Nouns stand alone, and context tells you whether something is specific or general. So perawat can mean “a nurse,” “the nurse,” or “nurses” depending on the situation.

What does the prefix mem- in membantu do?

mem- is a verb‐forming prefix in Indonesian that turns a root word into an active transitive verb. Because bantu starts with b, the prefix me- assimilates to mem-, giving membantu “to help.” Without the prefix, bantu is more like a base or command form.

Why is di used in di rumah sakit? Couldn’t we use ke or leave it out?

di is the preposition meaning “at” or “in” when indicating a static location. So di rumah sakit = “at the hospital.”
ke means “to” and marks motion toward a place (e.g. ke rumah sakit = “to the hospital”). If you omit the preposition entirely, it sounds like you’re just listing words, not specifying location.

How is rumah sakit formed? Why aren’t they linked by a particle?

rumah sakit is a compound noun: rumah = “house,” sakit = “sick.” Many Indonesian compounds are formed simply by putting two nouns together, with the modifier second showing the function or type. There’s no linking word (like “of” or “’s”) in standard compounds.