English usually moves a question word to the front and adds or inverts an auxiliary: “What did you buy?” Vietnamese generally leaves the question expression in the position where its answer would occur: Bạn mua gì? The sentence keeps ordinary clause order, the verb does not conjugate, and no Vietnamese word is inserted as English do.
The best repair is the answer-slot test: build a natural answer, replace only the unknown material, and preserve the surrounding Vietnamese structure. This page focuses on question-word placement and question type. It leaves the social force of sentence-final particles to Common Mistakes with Sentence-Final Particles.
Replace the answer in place
| Possible answer | Unknown slot | Natural question |
|---|---|---|
| Chị Lan gọi. | person as subject | Ai gọi? |
| Tôi gọi chị Lan. | person as object | Bạn gọi ai? |
| Tôi mua bánh mì. | thing as object | Bạn mua gì? |
| Tôi đi Đà Nẵng. | destination | Bạn đi đâu? |
| Tôi chọn chiếc áo xanh. | member of a set | Bạn chọn chiếc áo nào? |
| Tôi đi với ba người. | quantity | Bạn đi với bao nhiêu người? |
Chị đang tìm ai ở ngoài cổng?
Who are you looking for outside the gate?
Trưa nay anh muốn ăn gì?
What do you want to eat for lunch today?
Chiều mai anh đi đâu?
Where are you going tomorrow afternoon?
English fronts who/what/where. Vietnamese ai, gì, and đâu stay in subject, object, recipient, companion, or location slots. Initial ai in Ai gọi? is not fronted; it is already the subject.
Choose the question word by the missing information
| Expression | Requests | Important contrast |
|---|---|---|
| ai | a person; của ai asks whose | No everyday who/whom distinction |
| gì / cái gì | a thing, action, or category | gì is open; nào selects |
| nào | which member of a known set | Usually follows its noun: món nào |
| ở đâu / đi đâu | location or destination | Keep the locative relation the answer needs |
| khi nào / bao giờ | time | Can occupy a natural time-adjunct position |
| bao nhiêu / mấy | quantity | mấy often expects a small count; bao nhiêu is unrestricted |
| thế nào / làm sao | condition/manner or means/remedy | Not interchangeable in every context |
| tại sao / vì sao / sao | reason | Reason adjuncts commonly frame the clause initially |
Chị muốn thử món nào?
Which dish would you like to try?
Cuộc họp bắt đầu lúc mấy giờ?
What time does the meeting start?
Bạn đã trả bao nhiêu tiền?
How much did you pay?
Món gì? asks what kind of dish or what dish in an open way; món nào? asks which one from an understood set. Mấy combines naturally with classifiers or count nouns when a modest count is expected; bao nhiêu does not build in that expectation.
No do-support and no inversion
Vietnamese làm means “do/make” lexically. It cannot be inserted merely because English uses auxiliary do.
❌ Bạn làm mua gì ở chợ?
Incorrect — làm cannot translate question-forming ‘did.’
✅ Bạn mua gì ở chợ?
What did you buy at the market?
Likewise, the subject does not invert with a verb or auxiliary:
❌ Đâu bạn mua vé?
Incorrect neutral order — đâu has been fronted away from its location slot.
✅ Bạn mua vé ở đâu?
Where did you buy the ticket?
Time comes from context, aspect markers, and time expressions. The unchanged predicate mua can correspond to English buy, bought, or will buy.
Do not stack an open question with final không
An open content question asks for a missing person, thing, place, time, manner, quantity, or reason. Final không asks whether a proposition is true. Combining them changes the meaning or creates a conflict.
Anh đi đâu?
Where are you going?
Anh có đi đâu không?
Are you going anywhere?
The second is fully grammatical, but đâu is now an indefinite “anywhere” inside a polar frame. The expected answer is yes/no plus perhaps a destination, not necessarily a direct place name.
The same shift occurs elsewhere:
Ai cần giúp đỡ?
Who needs help?
Có ai cần giúp đỡ không?
Does anyone need help?
Anh cần gì?
What do you need?
Anh có cần gì không?
Do you need anything?
An “incorrect” form may therefore be grammatical with an unintended indefinite reading. Diagnose the requested answer before editing.
Reason questions and the in-situ principle
Tại sao, vì sao, and conversational sao often occur before the subject:
Vì sao sáng nay chị đến muộn?
Why did you arrive late this morning?
This does not license fronting every question word. A reason is a clause-level adjunct, and Vietnamese already permits such framing material at the clause edge. The internal proposition sáng nay chị đến muộn remains in declarative order. Vì sao is common in careful explanatory or academic contexts (formal/academic); short initial sao is conversational (informal) and can sound concerned, surprised, or accusatory.
Six English-triggered repairs
| Intended question | Transfer form | Repair | Diagnosis |
|---|---|---|---|
| Who are you waiting for? | Ai bạn đang đợi? | Bạn đang đợi ai? | Ai fills the object slot. |
| What did she buy? | Gì chị ấy đã mua? | Chị ấy đã mua gì? | Gì stays after mua. |
| Where are you going? | Đâu bạn đi? | Bạn đi đâu? | Đâu is the destination. |
| Which book do you want? | Nào sách bạn muốn? | Bạn muốn cuốn sách nào? | Nào follows the classifier-noun phrase. |
| Why didn't he call? | Tại sao anh ấy làm không gọi? | Tại sao anh ấy không gọi? | No English-style do-support. |
| How do I open this file? | Thế nào tôi mở tệp này? | Tôi mở tệp này bằng cách nào? | Bằng cách nào replaces the missing method after the predicate. |
Dialogue repair: open question or existence check?
Mai: Chiều nay anh có gặp ai không? — Huy: Có, anh có hẹn. — Mai: Ý em là em muốn hỏi anh sẽ gặp ai.
Mai: Are you meeting anyone this afternoon? — Huy: Yes, I have an appointment. — Mai: I mean, I want to know who you're meeting. (Mai's first grammar asked a polar question, not directly for identity.)
Mai: Chiều nay anh gặp ai? — Huy: Anh gặp chị Lan để bàn về hợp đồng.
Mai: Who are you meeting this afternoon? — Huy: I'm meeting Ms. Lan to discuss the contract.
The repaired question removes có...không because Mai wants an identity. Anh có gặp ai không? is grammatical and useful when she first wants to know whether he is meeting anyone at all. Question type determines the answer space.
Register and social calibration
Question-word syntax is stable across regions, but address terms and particles determine interpersonal force. Em đang đợi ai vậy? is natural among familiar speakers (informal). In a service or institutional setting, a fuller frame may be deferential: Thưa cô, em cần nộp đơn này cho ai ạ? (formal/deferential). Short Sao? or Gì? can sound abrupt depending on intonation. These particles and ellipses do not alter the answer-slot principle.
Common Mistakes
1. Fronting an object question word
❌ Ai em mời đến dự tiệc?
Incorrect neutral order — ai has been copied into English front position.
✅ Em mời ai đến dự tiệc?
Who did you invite to the party?
2. Inventing an auxiliary with làm
❌ Bạn làm biết mật khẩu thế nào?
Incorrect — làm is not an auxiliary equivalent to English ‘do.’
✅ Bạn biết mật khẩu bằng cách nào?
How do you know the password?
3. Adding final không to an open question
⚠️ Chị mua gì không?
A colloquial polar reading ‘Did you buy anything?’ is possible; it does not ask the open ‘What did you buy?’
✅ Chị mua gì?
What did you buy?
4. Confusing gì with nào
⚠️ Trong ba chiếc áo này, chị thích áo gì?
Understandable, but it asks about type rather than cleanly selecting one member of the visible set.
✅ Trong ba chiếc áo này, chị thích chiếc nào?
Which of these three shirts do you like?
5. Treating initial reason words as permission to front everything
❌ Đâu chị để chìa khóa?
Incorrect neutral word order; đâu is not a clause-framing reason adjunct.
✅ Chị để chìa khóa ở đâu?
Where did you put the keys?
Key Takeaways
- Vietnamese generally leaves question expressions in the slots their answers would occupy.
- Do not add English do-support, inversion, or tense changes to the verb.
- Ai/gì/đâu inside có...không often mean “anyone/anything/anywhere,” creating a polar question.
- Gì asks openly; nào selects from an understood set.
- Reason adjuncts can frame a clause initially without making object fronting grammatical.
- Choose question type first; sentence-final particles express stance and belong to the next dedicated page.
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Start learning Vietnamese →Related Topics
- Common Mistakes with Directional ComplementsB1 — Choose and position Vietnamese directionals by tracking the path, reference point, transported entity, and event boundary.
- Common Mistakes with Sentence-Final ParticlesB2 — Repair English-driven particle choices by matching Vietnamese sentence endings to speech act, relationship, and conversational stance.
- Ai for WhoA2 — Ask who did, received, owned, or accompanied something while leaving ai in its ordinary noun-phrase position.
- Gì for WhatA2 — Use gì in the missing thing, action, or category slot without English-style fronting or do-support.
- Ở Đâu and Đi ĐâuB1 — Distinguish location with ở đâu from destination with đi đâu and place each expression in its natural clause position.
- Thế Nào and Làm SaoB2 — Ask about quality, manner, condition, and possible solutions with thế nào and làm sao without importing English question order.