There are two ways to build a question in Chinese, and the single most persistent beginner error is trying to use both at once. Either a sentence contains a question word — 谁 (who), 什么 (what), 哪儿 (where), 怎么 (how), 为什么 (why) — sitting exactly where the answer will go, or it's a plain statement made interrogative by a final 吗. What you must never do is take a sentence that already has a question word and also tag 吗 onto it. The infamous ✗你去哪儿吗 is the poster child. Understanding why it's wrong — not just memorising the ban — makes it stick.
Two independent question strategies
Chinese asks questions in place: the question word occupies the slot of the missing information, and word order doesn't change.
| Strategy | Example | What it asks |
|---|---|---|
| Question word, in situ | 你去哪儿？ | where — expects a place |
| Question word, in situ | 你吃什么？ | what — expects a thing |
| Statement + 吗 | 你去吗？ | yes or no — expects 去 / 不去 |
| Statement + 吗 | 你吃吗？ | yes or no — expects 吃 / 不吃 |
你去哪儿？
nǐ qù nǎr
Where are you going? (neutral) — 哪儿 sits where the place-answer will go.
这是谁的手机？
zhè shì shéi de shǒujī
Whose phone is this? (neutral) — 谁 in place of the owner, no 吗.
你周末打算做什么？
nǐ zhōumò dǎsuàn zuò shénme
What do you plan to do this weekend? (informal) — 什么 already carries the question.
Why 吗 and a question word can't co-exist
The logic is clean. 吗 asks for a yes-or-no. A question word asks for a specific piece of information — a name, a place, a reason. You cannot answer "yes/no" to "where are you going?" and you cannot answer "Shanghai" to a "yes-or-no?" prompt. The two are asking for different kinds of answer, so gluing them together is a contradiction: 你去哪儿吗 literally tries to ask "yes-or-no, where are you going?" — incoherent. A sentence with 哪儿 in it is already a complete question; 吗 has nothing left to do.
❌ 你去哪儿吗？
Incorrect — 哪儿 already makes it a question; 吗 would demand a yes/no, which clashes. Drop 吗.
你去哪儿？
nǐ qù nǎr
Where are you going? (neutral) — the fix: question word alone.
呢 can follow a question word — 吗 cannot
Here's a subtlety that trips learners who've over-generalised the ban. While 吗 is forbidden after a question word, 呢 (ne) is welcome: it doesn't force a yes/no, it just softens the wh-question or adds a "so…?/well…?" mood. So the rule isn't "no particle after a question word" — it's specifically "no 吗."
你到底想说什么呢？
nǐ dàodǐ xiǎng shuō shénme ne
So what is it you actually want to say? (informal) — 呢 softens the wh-question; 吗 would be wrong here.
这么晚了，你去哪儿呢？
zhème wǎn le, nǐ qù nǎr ne
It's so late — where are you off to? (informal) — 呢 adds a curious, softened tone to 哪儿.
❌ 你想说什么吗？（meaning 'what do you want to say?')
Wrong for a wh-question — 什么...吗 turns it into 'do you want to say something?' (yes/no), not 'what?'. Use 呢 or nothing: 你想说什么(呢)?
The real exception: an indefinite question word
There's a genuine case where 吗 and a "question word" do appear together — but only because the word has stopped being a question word. 什么, 谁, 哪儿 can also mean "something / anything," "someone / anyone," "somewhere / anywhere." When 什么 means "anything," the sentence really is a yes/no question, and 吗 is correct.
| Sentence | 什么 = | Question type |
|---|---|---|
| 你想吃什么？ | "what" (interrogative) | wh-question — no 吗 |
| 你想吃什么吗？ | "anything" (indefinite) | yes/no question — 吗 correct |
你想吃点什么吗？我去买。
nǐ xiǎng chī diǎn shénme ma, wǒ qù mǎi
Do you want to eat anything? I'll go buy it. (informal) — 什么 = 'anything', so it's a genuine yes/no and 吗 fits.
你想吃什么？
nǐ xiǎng chī shénme
What do you want to eat? (neutral) — here 什么 = 'what', a wh-question, so no 吗.
The two differ in speech by stress and context, and in meaning entirely: one offers to fetch whatever you fancy (yes/no), the other asks you to name a dish. See indefinite uses of question words for the full pattern.
Common Mistakes
1. The classic double question — question word + 吗. The error that names this page.
❌ 他是谁吗？
Incorrect — 谁 already asks 'who'; 吗 clashes. Say 他是谁?
✅ 他是谁？
tā shì shéi
Who is he? (neutral) — question word alone.
2. Using 吗 to soften a wh-question (where you wanted 呢). If you want a gentler wh-question, the particle is 呢, not 吗.
❌ 你怎么还没来吗？
Wrong — a 怎么 (why/how) question can't take 吗; for the softened mood use 呢: 你怎么还没来呢?
✅ 你怎么还没来呢？
nǐ zěnme hái méi lái ne
How come you're still not here? (informal) — 呢 softens the 怎么 question.
3. Reading an indefinite-什么 sentence as a wh-question. 你要买什么吗 is "do you want to buy anything?", not "what do you want to buy?"
你要买什么吗？
nǐ yào mǎi shénme ma
Do you want to buy anything? (informal) — with 吗, 什么 means 'anything'; this is yes/no.
你要买什么？
nǐ yào mǎi shénme
What do you want to buy? (neutral) — no 吗, so 什么 means 'what'.
4. Assuming no particle may follow a question word. 呢 is perfectly fine; only 吗 is barred.
❌ 你为什么不去吗？
Incorrect — 为什么 is a wh-question; drop 吗 (or use 呢): 你为什么不去呢?
✅ 你为什么不去呢？
nǐ wèishénme bú qù ne
Why aren't you going? (informal) — 呢 is allowed after 为什么; 吗 is not.
Key Takeaways
- A sentence is a question in one way: a question word in situ OR a final 吗 — never both.
- 吗 demands a yes/no; a question word demands a specific fact — stacking them asks for two incompatible answer types.
- 呢 may follow a wh-question (softening it); 吗 may not. The ban is specifically on 吗.
- The one apparent exception is indefinite 什么/谁/哪儿 ("anything / anyone / anywhere") — then the sentence really is yes/no and 吗 is correct.
- Before saying 吗, ask yourself: "yes/no, or a fact?" If a fact, you already have a question word and 吗 is wrong.
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- 吗 (Yes/No Question Particle)HSK 1 — Append 吗 (ma) to any statement and it becomes a neutral yes/no question — no inversion, no 'do', no word-order change at all: 你是学生吗? 他来吗? 好吃吗?
- Question Words Stay In Place (In Situ)HSK 1 — The single most important rule for Chinese wh-questions: the question word sits exactly where the answer will sit. No fronting, no do-support, no reordering — 你去哪儿？ not ❌哪儿你去？ And because the question word already asks, you never add 吗.
- Question Words as 'Any / No' (谁都, 什么都, 哪儿也不)HSK 3 — The same word 什么 that asks 'what?' also means 'anything / something' — the frame around it decides. Put 都/也 after a question word and it turns universal (谁都 'anyone', 什么都 'everything'); add negation and it flips to 'no-one / nothing / nowhere' (什么都没买 'bought nothing').