Learn Hardcore Indonesian: Saya menaruh buku ke dalam tas.

saya = neutral/formal/polite; good for most situations.
aku = informal/intimate; used with friends/family. So you can say Aku menaruh buku ke dalam tas in casual contexts.

Can I omit the subject and just say the sentence without saya?

Often yes, if the subject is clear from context. For example:

Menaruh buku ke dalam tas. (context-dependent) More natural is to keep a subject or use the clitic ku-: Kutaruh buku ke dalam tas (I put the book into the bag).

Is menaruh the best verb here? What about meletakkan, memasukkan, or menyimpan?

They overlap but differ in nuance:

menaruh = to put/place (general).
meletakkan = to put/place down (often onto a surface).
memasukkan = to put something into something (movement into).
menyimpan = to put away/keep/store (for safekeeping). For a bag:
Most precise: Saya memasukkan buku ke dalam tas.
Also idiomatic: Saya menaruh buku di dalam tas. Your sentence Saya menaruh buku ke dalam tas is common and acceptable, though some prefer the pairings above.

What’s the difference between ke, di, ke dalam, and di dalam?

ke = to/toward (motion).
di = at/in/on (location).
ke dalam = into (motion to the inside).
di dalam = inside/in the inside (location, more explicit than just di). So: memasukkan … ke dalam … (into), vs menaruh … di dalam … (placed inside).

Can I say ke tas or di tas instead of ke dalam tas / di dalam tas?

ke tas can be understood as “to the bag,” and in casual speech often implies “into,” but it’s less explicit.
di tas usually means “in the bag” (context helps). “On top of the bag” would be di atas tas.
ke dalam tas / di dalam tas removes ambiguity by emphasizing the inside.

Why is there no “a/the” before buku? How do I say “a book” or “the book”?

Indonesian has no articles. buku can mean “book/a book/the book” depending on context. To be explicit:

a book: sebuah buku or satu buku
the/that book: buku itu
this book: buku ini

How do I make “books” plural?

Context often shows plurality. To be explicit:

general plural: buku-buku
some books: beberapa buku
many books: banyak buku Example: Saya menaruh beberapa buku ke dalam tas.

Why is it menaruh and not something like mentaruh? What happened to the initial t in taruh?

The verb uses the meN- prefix. With roots starting with t, the t drops and the prefix becomes men-:

taruh → menaruh Other examples:
tulis → menulis
tarik → menarik
pilih → memilih (p drops → mem-)
kirim → mengirim (k drops → meng-)
sikat → menyikat (s drops → meny-)

Can I replace buku with “it”?

Yes: Saya menaruhnya ke dalam tas. Here -nya = “it/that/his/her,” referring to a previously known item.

How do I say “my bag,” “your bag,” “his/her bag”?

my bag: tas saya or tasku
your bag: tas kamu or tasmu
his/her bag: tasnya Example: Saya menaruh buku ke dalam tasku.

How do I show past or future? Does the verb change?

The verb doesn’t change. Use time/aspect words:

past/completed: sudah, tadi, kemarin (e.g., Saya sudah menaruh…)
future: akan, nanti (e.g., Saya akan menaruh…)
ongoing: sedang (e.g., Saya sedang menaruh…)

Is ke dalam one word or two? I’ve seen kedalam.

Write it as two words: ke dalam (“into”). One-word forms with ke- are derivational prefixes (e.g., kedalaman = “depth”), not the preposition.

Are there passive versions of this sentence?

Yes, common options:

Long passive: Buku ditaruh ke dalam tas (oleh saya).
With object fronting (very natural): Buku saya taruh ke dalam tas.
Using memasukkan: Buku dimasukkan ke dalam tas.
With 1st-person clitic subject: Buku kutaruh ke dalam tas.

Is menaruhkan correct?

Not for “to put/place.” Use menaruh. Forms like pertaruhkan/ditaruhkan relate to “stake/wager,” a different sense of taruh.

What’s a natural colloquial version?

In casual Jakarta-style speech, people often say:

Gue naruh buku ke tas. (dropping the prefix to naruh, and often just ke tas) For standard usage, stick with Saya menaruh… / Saya memasukkan….

How do I negate the sentence correctly?

Use tidak before the verb:

Saya tidak menaruh buku ke dalam tas. If you want “not this book (but another),” negate the noun phrase with bukan:
Saya menaruh bukan buku itu ke dalam tas. (rare and contrastive; usually rephrase)

Where do demonstratives like ini/itu go?

They follow the noun:

buku itu = that/the book
tas ini = this/the bag Example: Saya menaruh buku itu ke dalam tas ini.