For ask questions in Japanese, you don't need to invert the sentence as you do in Portuguese. In polite yes/no questions, keep the statement structure and add か at the end. To ask “who”, “where”, “when” or “what”, place the question word in the corresponding group and preserve the particle that indicates its function.
日本語を勉強しますか。
Nihongo o benkyō shimasu ka.
Do you study Japanese?何を勉強しますか。
Nani o benkyō shimasu ka.
What do you study?
The first question confirms information. The second asks for the missing information. In both cases, the predicate remains at the end and を keeps the object function. This is the practical rule that organizes the rest of this guide.
Yes/no questions with か
In polite speech, a sentence ending in です or ます can become a question with か. There is no need to change the order of the groups:
- これは本です。
Kore wa hon desu.
This is a book. - これは本ですか。
Kore wa hon desu ka.
Is this a book? - 田中さんは来ます。
Tanaka-san wa kimasu.
Tanaka is coming. - 田中さんは来ますか。
Tanaka-san wa kimasu ka.
Is Tanaka coming?
The material Irodori, by the Japan Foundation, presents this pattern in questions like ～は、どこですか and ～は、どこにいますか. In pronunciation, intonation helps the listener, but the grammatical form is already marked by か.
Essential question words
An open question contains a word that represents the unknown information. It doesn't need to appear at the beginning of the sentence: it occupies the place where that information would make sense.
| Japanese | Reading | Basic usage | Short example |
|---|---|---|---|
| 何 | nani / nan | what; which | 何を食べますか。 — What will you eat? |
| 誰 | dare | who | 誰が来ますか。 — Who is coming? |
| どこ | doko | Where | どこで勉強しますか。 — Where do you study? |
| いつ | itsu | when | いつ行きますか。 — When are you going? |
| dō | dō | how; in what way | どうやって行きますか。 — How are you going? |
| どうして | dōshite | why | どうして勉強しますか。 — Why do you study? |
| どれ | dore | which among options | どれが好きですか。 — Which one do you like? |
| いくら | ikura | how much does it cost | これはいくらですか。 — How much does this cost? |
何 can be read as nani or nan according to the expression. To delve deeper into this pronunciation without straying from the general topic, refer to the specific guide on when to use nan or nani.
The particle continues after the interrogative word
It's not enough to just “swap the object” for any interrogative word. First, find out what information is missing; then choose the particle that marks the relationship of that group with the predicate. The guide on particles in Japanese helps review these functions.
- 何を読みますか。
Nani o yomimasu ka.
What are you going to read? — を marks the object of 読みます. - 誰が来ましたか。
Dare ga kimashita ka.
Who came? — が marks who performed the action. - どこに行きますか。
Doko ni ikimasu ka.
Where are you going? — に marks the destination. - Where do you study Japanese?
Doko de nihongo o benkyō shimasu ka.
Where do you study Japanese? — で marks the location of the activity. - 誰と話しましたか。
Dare to hanashimashita ka.
Who did you talk to? — と marks the companion.
words like いつ and どうして often function adverbially, without a particle right after: いつ日本へ行きますか (“When are you going to Japan?”) and どうして日本語を勉強していますか (“Why are you studying Japanese?”).
Formal questions and informal questions
The pattern with ですか or ますか is safe in polite situations. In informal conversations, it is common to use the plain form with question intonation and, in writing, the question mark:
- Polite: 明日、行きますか。 — Ashita, ikimasu ka. — Are you going tomorrow?
- Informal: 明日、行く？ — Ashita, iku? — Going tomorrow?
- Polite: 何を食べますか。 — Nani o tabemasu ka. — What are you going to eat?
- Informal: 何食べる？ — What should I eat? — What are you going to eat?
Do not add か mechanically to every informal question. Forms like 行くか exist, but they can sound masculine, abrupt, rhetorical, or context-dependent. For beginners, it is better to first master the opposition between 行きますか and 行く？.
What changes with ～んですか
The ending ～んですか is not just a longer version of ～ますか. It usually asks for an explanation or confirms something the speaker relates to the situation. Compare:
- 日本へ行きますか。
Nihon e ikimasu ka.
Are you going to Japan? — neutral question about the fact. - どうして日本へ行くんですか。
Dōshite Nihon e iku n desu ka.
Why are you going to Japan? — asks for the reason linked to the context.
O NINJAL explains the contextual role of のだ／んです: the speaker signals that they have part of the information and asks the listener to complete what is not yet clear. Depending on the situation and tone, the same form can also seem insistent; therefore, it should not be applied automatically.
How to respond naturally
In yes/no questions, はい and いいえ can start the answer, but adding the predicate avoids ambiguity. In open questions, answer with the requested information. What is already clear can be omitted.
A: 日本語を勉強しますか。
Nihongo o benkyō shimasu ka.
Do you study Japanese?B: はい、勉強します。
Hai, benkyō shimasu.
Yes, I study.A: どこで勉強しますか。
Doko de benkyō shimasu ka.
Where do you study?B: 家で勉強します。
Ie de benkyō shimasu.
I study at home.
In questions with どうして, an answer with からです presents the reason: 日本の映画が好きだからです (“Because I like Japanese movies”). から is a common resource, not the only possible way to explain a cause.
Common mistakes when formulating questions
- Inverting the sentence as in Portuguese. In Japanese, keep the predicate at the end. Review the word order in Japanese if there is still doubt.
- Removing the necessary particle. In 何を読みますか, 何 represents the object, but を continues to mark its function.
- Treating いつ, 誰 and どこ as objects. Each word can represent time, person, or place and relates differently to the predicate.
- Using か in all informal conversation. Casual register often uses the simple form and intonation.
- Confusing どこに and どこで. Use に for destination or location of existence and で for the place where an action happens.
- Repeating the entire question in the answer. If the topic is already clear, answer only with the new information and the necessary predicate.
Exercise: complete the questions
Choose the appropriate interrogative word or particle.
- （ ）日本語を勉強しますか。 — Where do you study Japanese?
- 誰（ ）来ましたか。 — Who came?
- 何（ ）食べますか。 — What are you going to eat?
- （ ）日本へ行きますか。 — When are you going to Japan?
Answers: 1. どこで; 2. が; 3. を; 4. いつ. In each case, observe whether the blank asks for the unknown information, the grammatical relation, or both.
To continue with request and choice situations, the Irodori grammar exercise sheets bring questions like 何にしますか and short everyday dialogues.
Next step: turn statements into questions
Start with a short sentence from the method of Japanese sentence formation. First make a yes/no question with か; then replace only one piece of information with 何, 誰, どこ or いつ and keep the appropriate particle. This contrast helps learn the structure without memorizing isolated lists.
Frequently asked questions about questions in Japanese
Is it mandatory to use か in every Japanese question?
No. In polite questions, ですか and ますか are safe patterns. In informal conversation, the plain form with question intonation, like 行く？, is very common. Adding か to an informal form can produce different register effects and should not be done mechanically.
Does Japanese need a question mark?
Not always. In formal writing, the particle か and context can make the question clear even with the Japanese period 。. The ？ mark is common in messages, dialogues, and informal texts, especially when the question relies on intonation.
What is the difference between どこに and どこで?
Where do you usually ask about a destination or location of existence, such as どこに行きますか and どこにありますか. どこで asks about the place where an action happens, such as どこで勉強しますか.
When is 何 read as nan or nani?
Reading depends on the expression and the following sound. In 何を, the reading is usually nani; in 何ですか, nan is used. Since there are other patterns, the specific article on nan and nani is the best place to study this difference.
How to ask “why” in Japanese?
どうして is a common option for beginners: どうして日本語を勉強していますか means “Why do you study Japanese?”. The reason can be presented with からです, but other constructions are also possible depending on the context and register.