かmakes a question; or
か at the end of a sentence turns it into a question. Between two choices it means "or".
A question
Polite sentence + か
です → ですか, ます → ますか, ました → ましたか. Nothing else changes. In writing it ends with 。; no question mark is needed.
Or
Noun + か + noun
A particle comes once, after the second noun: コーヒーか紅茶を.
A or B?
A ですか、B ですか
To ask someone to choose: two questions, one after the other.
Asking a question
English changes the word order or adds "do". Japanese adds か and leaves every word where it was.
Do you understand Japanese?
Has the meeting already ended?
A question word goes where the answer will go. It stays there; nothing moves to the front.
What is your name?
何 sits in the same place as 佐藤.
そうですか
You will hear this all day. Said with a falling voice it is not a question. It means "I see". With a rising voice it asks "is that right?".
It takes twenty minutes to walk to the station.
I see. Then I'll go by bus.
With friends, no か
In casual talk the か usually goes, and the voice rises at the end. In writing, ？ shows the rise.
Sounds odd: もう
Have you had lunch yet?
Blunt. Mostly men say it, older more than younger, to family or juniors.
In a casual question です goes too, and だ doesn't take its place.
Are you okay?
Not said: 大丈夫だ？
(Are you okay?)
A か you say to yourself is another matter. The voice falls, nobody is being asked, and it is a decision or something you have just taken in.
Right, time to go home.
Oh, of course, it's Sunday today.
A か B: or
I'll go on Saturday or Sunday.
Please let me know by phone or email.
Asking someone to choose
English asks "Monday or Tuesday?" as one question. Japanese asks two questions, one after the other.
Is the meeting on Monday or Tuesday?
Which day is it? The answer is a day.
Is the meeting on Monday or Tuesday?
A yes-or-no question: is it one of those two days?
Whether to do one thing or the other
Inside a longer sentence, each choice is a plain verb with its own か. A verb like 決める (decide) or わかる comes after.
I have not decided yet whether to go by train or by bus.
Close neighbours
ませんかN5
Usually an invitation, not a negative question: "would you like to…?"
Would you like to see a movie together?
〜か知っているN4
A question with a question word, tucked inside a longer sentence.
I know where Mr. Tanaka lives.
Check yourself
1"Where is the restroom?"
Choose an answer to see why.
2To a close friend: "Are you free tomorrow?"
Choose an answer to see why.
3"Please come on Monday or Tuesday."
月曜日
Choose an answer to see why.
More detail
Answering yes
When the question ends in a noun and ですか, the answer is はい、そうです. After a verb or an adjective, people say the word again instead.
Is this Tanaka's umbrella?
Is this room quiet?
More sentences
Is that movie interesting?
What time does the store open?
Is lunch curry or pasta?
Is the entrance on the right or the left?
Will you choose the red bag or the black bag?
I am still deciding whether to cook tonight or eat out.
Please decide whether to open or close the window.