Sách này thuộc thư viện.

• sách = book
• này = this
• thuộc = to belong to / to be under
• thư viện = library

So the structure is basically:

book + this + belong to + library

Vietnamese often builds sentences in a more compact way than English.

In Vietnamese, words like này (this) usually come after the noun they describe.

So:

• sách này = this book
• người này = this person
• nhà này = this house

This is a very common word order pattern in Vietnamese.

Vietnamese does not normally use articles like English a / an / the.

So sách can mean:

• a book
• the book
• just book in a general sense

The exact meaning depends on context. In this sentence, này makes it specific, so sách này clearly means this book.

Because thuộc is already the main verb here.

• là is often used for to be in definitions, identification, or equivalence:
  • Đây là thư viện. = This is a library.
• But in Sách này thuộc thư viện, the verb is thuộc = belongs to

So adding là would be wrong here.

Here, thuộc means belongs to or is under the ownership/control of.

So Sách này thuộc thư viện means the book is part of the library’s collection, not someone’s personal book.

thuộc can also be used in other contexts, such as:

• thuộc công ty này = belongs to / is under this company
• thuộc về ai = belongs to whom

So it is a useful word for possession, membership, or being under an organization.

Good question. Both can relate to possession, but they work differently.

• thuộc is a verb: to belong to
• của is more like of / ’s

Compare:

• Sách này thuộc thư viện. = This book belongs to the library.

• Sách này là của thư viện. = This book is the library’s / This book is of the library.

Both are natural.
thuộc sounds a bit more formal or institutional in some contexts, while là của can sound more direct and conversational.

Vietnamese often uses classifiers, but they are not always required.

You could say:

• Cuốn sách này thuộc thư viện.
• Quyển sách này thuộc thư viện.

These both mean the same thing as Sách này thuộc thư viện.

Without a classifier, the sentence is still completely natural. Vietnamese often omits classifiers when the noun is already clear and the sentence is straightforward.

Vietnamese does not force that distinction the way English does.

So thư viện can mean:

• a library
• the library

Context tells you which one is intended.

In a real situation, Sách này thuộc thư viện often implies the library that both speaker and listener already know about, such as a school library or public library.

Yes, it is natural and correct.

It is simple, clear, and common, especially in contexts like:

• identifying library property
• explaining where a book comes from
• telling someone the book is not privately owned

A very common alternative is:

• Cuốn sách này là của thư viện.

That version may sound slightly more conversational to some speakers, but the original sentence is perfectly fine.

It can suggest both, depending on context.

With a book, thuộc thư viện usually means:

• it belongs to the library
• it is part of the library’s collection

So the idea is not only strict ownership in a legal sense, but also that the book is under the library’s system or management.

A rough pronunciation guide is:

• Sách → somewhat like sahk with a sharp rising/checked tone
• này → like nye with a falling tone
• thuộc → roughly thoo-uhk with a heavy falling/checked tone
• thư viện → roughly thuh vee-en with Vietnamese vowel sounds

The tones matter a lot in Vietnamese, so it is best to learn them from audio if possible. The spelling alone does not fully show an English speaker how it sounds.

Yes.

For example:

• Sách này thuộc thư viện. = This book belongs to the library.
• Sách đó thuộc thư viện. = That book belongs to the library.
• Sách kia thuộc thư viện. = That book over there belongs to the library.

So the noun stays first, and the demonstrative changes depending on distance or context.

No, that word order is not normal in Vietnamese.

The natural order is:

noun + demonstrative

So:

• sách này = correct
• này sách = incorrect

This is one of the first word-order differences English speakers need to get used to in Vietnamese.