Jag vill fråga efter den boken i biblioteket.

I want to ask for that book in the library.

Breakdown of Jag vill fråga efter den boken i biblioteket.

• jag: I
• i: in
• boken: the book
• vilja: to want
• biblioteket: the library
• den: that
• fråga efter: to ask for

Questions & Answers about Jag vill fråga efter den boken i biblioteket.

Why do you say fråga efter and not just fråga?

Swedish distinguishes between:

• fråga någon (om något) – to ask someone (about something), i.e. to pose a question.

  • Jag vill fråga bibliotekarien om öppettiderna. = I want to ask the librarian about the opening hours.

• fråga efter något – to ask for something, i.e. to request something you want to get/obtain.

  • Jag vill fråga efter den boken. = I want to ask for that book.

In your sentence you are requesting a book, not asking a question about it, so fråga efter is the natural choice.

What is the difference between fråga efter and fråga om?

• fråga efter något = "ask for something" (you want someone to give or bring it):

  • Jag ska fråga efter menyn. = I’ll ask for the menu.

• fråga om något = "ask about something" (you want information about it):

  • Jag ska fråga om menyn. = I’ll ask about the menu (e.g. what’s on it, how it works).

So, Jag vill fråga efter den boken i biblioteket means you want to request that book, not just talk about it.

Why is it den boken and not just boken?

Both are possible, but they have slightly different nuances:

• boken = the book in a neutral, definite sense:

  • Jag vill fråga efter boken i biblioteket.
    = I want to ask for the book in the library.

• den boken = that book / that particular book, more specific or contrastive:

  • Jag vill fråga efter den boken i biblioteket.
    = I want to ask for that (specific) book in the library (maybe not another one).

So den boken adds a bit of pointing/emphasis: that one, the one we have in mind, as opposed to other books.

Why do we need both den and the ending -en in den boken? Isn’t that “double definite”?

Yes, Swedish normally uses "double definiteness" with demonstratives and adjectives:

• Without demonstrative/adjective:

  • bok = a book
  • boken = the book

• With demonstrative or adjective, you keep the definite noun ending and add a determiner:

  • den boken = that/the book
  • den röda boken = the red book / that red book

This is just how standard Swedish works: when you use den/det/de or an adjective, you keep the definite ending on the noun as well.

Why is it den and not det in den boken?

Because bok is an en-word (common gender):

• en bok – boken
• den boken

For ett-words (neuter), you use det:

• ett hus – huset – det huset (that house)
• ett bibliotek – biblioteket – det biblioteket (that library)

So:
den boken (that book) but det huset (that house).

Is i biblioteket the same as på biblioteket? Which sounds more natural?

Both are grammatically correct, but they feel slightly different:

• på biblioteket is the most natural for "at the library" as a place where things happen:

  • Jag vill fråga efter den boken på biblioteket.
    = I want to ask for that book at the library.

• i biblioteket focuses more on being inside the building:

  • Jag gick runt i biblioteket. = I walked around in the library.

In many everyday contexts Swedes would say på biblioteket here, but i biblioteket is not wrong; it just has a more literal “in the building” feel.

Could I say Jag vill fråga efter boken i biblioteket instead? Does it change the meaning?

Yes, that is correct Swedish, and the meaning is almost the same. The nuance:

• fråga efter boken – the book, understood from context, but somewhat neutral.
• fråga efter den boken – that particular book, more clearly pointing to a specific one you and the listener have in mind or are contrasting with others.

So you can use either, depending on how strongly you want to point to a specific book.

Why is there no att before fråga? In English we say “I want to ask…”.

In Swedish, modal verbs like:

• vill (want)
• kan (can)
• ska (shall / going to)
• måste (must)

are followed directly by the infinitive without att:

• Jag vill fråga… = I want to ask…
• Jag kan läsa. = I can read.
• Jag ska äta. = I’m going to eat.

You do use att with non-modal verbs:

• Jag hoppas att fråga imorgon is not idiomatic.
• Jag hoppas att jag kan fråga imorgon. = I hope that I can ask tomorrow.

So Jag vill fråga efter den boken… is the correct structure.

Can I move i biblioteket earlier in the sentence, like I biblioteket vill jag fråga efter den boken?

Yes, that is grammatically correct, but it sounds more marked and is usually used for emphasis or in written style:

• Jag vill fråga efter den boken i biblioteket.
  – neutral, everyday word order.

• I biblioteket vill jag fråga efter den boken.
  – emphasises in the library (e.g. “Not online, but in the library I want to ask for that book”).

Swedish main clauses must keep V2 word order: the finite verb is in second position, so when you move i biblioteket to the front, the next element must be vill:

• I biblioteket vill jag… ✔
• I biblioteket jag vill… ✘ (ungrammatical)

How would I say this in the past tense: “I wanted to ask for that book in the library”?

You just put vill in the past tense (ville), and keep the rest the same:

• Jag ville fråga efter den boken i biblioteket.

Other small adjustments are possible (e.g. på biblioteket), but the main tense change is:

• vill → ville.