だれ / なに・なん / どこ / いつ

To ask who, what, where, or when, Japanese does not front the question word the way English does. It leaves it in place — sitting exactly where the answer would go — and closes the sentence with か or a rising pitch. This page is about building those content questions: the recipe, and the one thing that determines the shape of each one — the particle the slot demands. (For the meanings and particle quirks of each word in depth, the question-words pages go deeper; here we focus on how the question is assembled.)

The recipe: imagine the answer, swap in the question word

Because the question word never moves, a content question and its answer share their word order almost perfectly. So the fastest way to build one is: picture the statement you'd expect as an answer, replace the unknown piece with the matching question word, and mark the sentence.

寿司 ("sushi") and 何 ("what") occupy the identical slot — object, marked with を — and everything else is untouched. There is no wh-fronting and no do-support. This "leave it in place" behavior runs all the way into embedded questions too; see embedded wh-questions with か.

だれ (誰) — who

誰（だれ）"who" is grammatically an ordinary noun, so when you build the question it takes whatever particle its slot requires — が as subject, を as object, に for the person affected, と for "with whom," の for possession. You do not front it; you park it in the answer's slot with the answer's particle.

Note 誰が in the first example, not ×誰は — more on why just below. The full particle line-up for 誰 (誰に会う, 誰と行く, 誰の…) is drilled on 誰・どこ・いつ, and the polite substitute is どなた.

なに / なん (何) — what

何 "what" is the workhorse content word, and the only wrinkle in building a question with it is its reading, which flexes with the sound that follows. When you assemble the question, the kanji 何 is fixed but you must know whether to say なに or なん:

• Before を / が / も and standing alone → なに: 何を (nani o), 何が (nani ga).
• Before the copula です／だ, a counter, の, or a t/d/n sound → なん: 何です (nan desu), 何時 (nanji), 何の (nan no).

Same kanji, two readings — なに before を, なん before です — driven purely by phonology, not by which question you're asking. The complete rule (and the meaning-bearing pairs like 何人 なんにん "how many" vs なにじん "what nationality") is on 何: なに or なん.

どこ — where

どこ "where" is a plain place-noun, so building a where-question means choosing the location particle the verb calls for — the same で / に / へ logic as any statement: で for the venue of an action, に for existence or destination, へ for direction.

待ち合わせ ("meeting up") is an action performed at a place → で; 置く ("put/place") sets something down at a spot of resulting existence → に. Picking correctly is ordinary particle practice, laid out on 誰・どこ・いつ. The polite form is どちら.

いつ — when

いつ "when" is the odd one: it is a relative time word, so — unlike a clock or calendar point — it takes no に. You ask いつ帰りますか, never ×いつに帰りますか. It does combine freely with から ("since when") and まで ("until when").

That last example stacks two question words — いつ and どこで — and, tellingly, both stay in place: いつ in the time slot, どこ in the place slot, each with its own particle (どこで, いつ with none). English would have to pick one to front; Japanese leaves them where they belong. Why いつ refuses に is explained on 誰・どこ・いつ.

The two syntax rules that govern all four

Building these questions comes down to two facts that hold for every content word:

1. The question word stays in place. It sits in the answer's slot with the answer's particle; nothing is fronted. This is the single hardest habit for English speakers to switch off, because English obligatorily moves wh-words to the front.

2. In subject position, take が, not は. A question word asks for brand-new, unknown information, and は marks known topics — so an interrogative subject is marked with が.

Saying ×誰はこのケーキを作ったんですか is a classic beginner error: you cannot present an unknown as a known topic. The logic runs through the whole language — see は vs が: new versus known.

Common Mistakes

The recurring theme: build the question in statement order, give the word the particle its slot demands (が for unknown subjects, で/に by the verb, no に for いつ), and read 何 by what follows it.

Key Takeaways

• Build a content question by imagining the answer and swapping in the question word — same word order, question word in place, then か or rising pitch.
• だれ (誰) and どこ take whatever particle the slot needs; どこ follows the で/に/へ location logic.
• なに / なん (何) is one kanji with a phonology-driven reading split: なに before を/が, なん before です/counters/の/t·d·n.
• いつ takes no に (it's a relative time word) but pairs with から/まで.
• Two rules hold across all four: no fronting (the word stays put) and が, not は, for an unknown subject.