We use "desu" and "deshita" to make the polite form and "ka" to make it a question, for example:

Tokyo ga suki desu ka? (Do you like Tokyo?)
Tokyo ga suki deshita ka? (Did you like Tokyo?)

How can I ask the same questions using the dictionary, casual forms of "desu" and "deshita" which are "da" and "datta"?

Should I add "ka" at the end of a sentence? Or just replace "desu" and "deshita" with "da" and "datta"?

P.S. I don't need a long explanation, but rather a simple answer. The information I've found so far is ambiguous.


How common and ok to use this in informal speech (without ka)?:

Tokyo ga suki da/datta?

Just yes or no.


All of desu, deshita, and datta appear normally before ka.

But da is an exception. In main clauses (like your examples), da is deleted before ka:

 desu    + ka   →   desu ka
 deshita + ka   → deshita ka
 da      + ka   →        ka
 datta   + ka   →  datta ka

In subordinate clauses (like [dare da ka] shiranai), da sometimes appears before ka.

Although you want a short answer, you should also consider alternate ways of forming questions, for example using rising intonation, omitting ka. In informal speech, people don't always use the textbook-style question with ka at the end.

  • ... As well as in case of "datta". For example, Tokyo ga suki da/datta? Is that acceptable? I don't want to dig into the details.
    – Oskar K.
    Aug 29 '15 at 13:50
  • 2
    @jawanam - da? is not acceptable. - datta? is OK because you have the form after you putting ka? and removing ka. Aug 29 '15 at 14:01
  • because you have the form after you putting ka? -- what does that mean exactly?
    – Oskar K.
    Aug 29 '15 at 14:17
  • 1
    @jawanam I mean, if you start with suki datta., you'll get suki datta ka?, then suki datta?. But with suki da., you'll get suki ka?, then suki?. So datta? actually exists but you can't assume simply that plain ending + ? would make a question. Aug 29 '15 at 14:28

I try to be simple, but there's always something that needs explanation.

Should I add "ka" at the end of a sentence? Or just replace "desu" and "deshita" with "da" and "datta"?

Grammatically you can have them (see @snailboat's answer), but I'm not sure if you should. The reason is that, plain form + ka often sounds too harsh, unless you're a manly man talking to your child or lover. Otherwise it simply sounds like a rigid boss, a soldier, or a police officer (during interrogation). To avoid that, you should omit ka and say Tokyo ga suki (datta)?, where the ? is accompanied with rising intonation.

The main use of plain form + ka is to form indirect speech.

Tokyo ga suki (datta) ka to kikareta.
I was asked if I (had) liked Tokyo.

  • To avoid that, you should remove ka and say Tokyo ga suki (datta) - and where is "da"? Can't I say Tokyo ga suki da?
    – Oskar K.
    Aug 29 '15 at 13:44
  • 1
    @jawanam No. Tokyo ga suki da. → add ka for question → Tokyo ga suki ka? (da removed) → omit kaTokyo ga suki? Aug 29 '15 at 13:51
  • and how would I reply to Toky ga suki ka? With "da" --> "suki da"?
    – Oskar K.
    Aug 29 '15 at 14:18
  • In addition to the harshness mentioned in your answer, plain form + か is -- with the right tone of voice -- a rhetorical question. Rhetorical questions sometimes have a pause before the か → 「そういうこと…か」
    – oals
    Aug 29 '15 at 14:29
  • @jawanam Both basically work, with or without. That would be another complicated question if you want to know :) Aug 29 '15 at 14:31

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