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.

  • Interesting, I thought in case of "da" we dropped "ka" and not "da" itself (as I was told). – Oskar K. Aug 29 '15 at 13:47
  • There's probably a lot more I should have added, but I was trying to keep it short… – snailplane Aug 29 '15 at 13:49
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    @jawanam - da? is not acceptable. - datta? is OK because you have the form after you putting ka? and removing ka. – broken laptop Aug 29 '15 at 14:01
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    @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. – broken laptop Aug 29 '15 at 14:28
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    @broccoliforest, indeed, otherwise there's no way to say whether or not it's a past tense. – Oskar K. Aug 29 '15 at 14:40

I try to be simple, but there's always something need 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
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    @jawanam No. Tokyo ga suki da. → add ka for question → Tokyo ga suki ka? (da removed) → omit kaTokyo ga suki? – broken laptop 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 :) – broken laptop Aug 29 '15 at 14:31

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