không biết + Question Word

Indirect Question

Level 3

Use không biết followed by a normal question clause to say you don't know something. The word order stays exactly the same as a regular question.

How It Works

1. Stating Ignorance
To say you don't know a specific fact, use không biết + [Clause with a Question Word].

  • Anh ấy ăn gì? (What is he eating?)
  • Tôi không biết anh ấy ăn gì. (I don't know what he is eating.)

Notice that there is no "Wh-fronting" like in English. The question word stays exactly where it belongs in the sentence.

2. Polite Softener
Native speakers frequently use this pattern not to state ignorance, but as a polite way to ask a question, similar to "I wonder..." or "May I ask...". When using it this way, native speakers almost always drop the subject pronoun Tôi, as including it can sound like a blunt statement of fact. You can also add the respect particle ạ when speaking to someone older or of higher status.

  • Không biết anh tên gì ạ? (May I ask what your name is?)

3. Yes/No Indirect Questions
Unlike the Wh- questions above, Yes/No indirect questions use grammatical frames instead of actual question words. If you want to say "I don't know if/whether...", do not use the conditional word nếu. You can use liệu (whether) as in the I Wonder Whether pattern, or simply use standard yes-no question frames. For present/future actions, use the Yes-No Question frame:

  • Tôi không biết anh ấy có đến không. (I don't know if he is coming.)

You might also hear hay không at the end of the sentence to mean "whether or not" (e.g., Tôi không biết anh ấy có đến hay không.).

For past or completed actions, use the Have You Yet? frame (often with đã):

  • Tôi không biết anh ấy đã đến chưa. (I don't know if he has arrived.)

Note: In casual Southern speech, không is often pronounced as hông or hong. Also, while some people might insert là (Tôi không biết là...), it is completely optional and often omitted in natural speech.

Examples (6)

  1. Cô ấy không biết khi nào em đến.

    She doesn't know when you're arriving.

    Word by Word: She not know when you arrive.

    Notice how the question word 'khi nào' stays in its natural position.

  2. Mình không biết nhà nó ở đâu.

    I don't know where his house is.

    Word by Word: I not know house his at where.

    A standard indirect question. Do not confuse the question word 'đâu' here with the emphatic denial particle.

  3. Tôi không biết bạn học tiếng Việt được bao lâu rồi.

    I don't know how long you have been studying Vietnamese.

    Word by Word: I not know you study language Vietnamese achieve how long already.

    The entire question clause remains exactly the same as if you were asking it directly.

  4. Không biết anh tên gì?

    May I ask what your name is? / I wonder what your name is.

    Word by Word: Not know older brother name what?

    Here, 'không biết' is used pragmatically as a polite softener rather than a literal statement of ignorance.

  5. Tôi không biết liệu ngày mai trời có mưa không.

    I don't know whether it will rain tomorrow.

    Word by Word: I not know whether tomorrow sky have rain not.

    To say 'whether', you can use 'liệu' combined with the standard 'có ... không' frame. Never use 'nếu' (if) here.

  6. Tôi không biết anh ấy đã đến chưa.

    I don't know if he has arrived.

    Word by Word: I not know he already arrive not yet.

    For past or completed actions, use the 'đã ... chưa' frame instead of 'có ... không'.

Common Mistakes

  • Moving the question word to the front of the clause (Wh-fronting).

    Tôi không biết gì anh ấy ăn.
    Tôi không biết anh ấy ăn gì.

    English moves question words like 'what' to the front ('I don't know what he eats'). Vietnamese keeps the question word in its original grammatical slot (Subject + Verb + Object).

  • Using 'nếu' (if) for yes/no indirect questions.

    Tôi không biết nếu anh ấy đến.
    Tôi không biết liệu anh ấy có đến không.

    'Nếu' is only used for conditional 'if... then...' statements. For 'I don't know if/whether...', use 'liệu' or simply the standard yes/no question structures like 'có ... không' or 'đã ... chưa'.

How It Connects

Tap a pattern to see what it builds on and what it leads to.

không biết + Question WordLevel 3Indirect Question

Learn This First

To understand indirect questions in Vietnamese, you first need to know the verb 'biết' (to know) and how to negate it with 'không'. Crucially, you must understand that Vietnamese uses 'wh-in-situ', meaning question words (like 'what', 'where', or 'who') stay in the same place in the sentence regardless of whether it is a direct or indirect question.

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Words in This Pattern

biết