Using か in casual speech


There are definitely many questions about the usage (or lack thereof) of か in
casual speech. Although it is relatively common in anime, it sounds harsh,
maybe rude in everyday casual speech.

Alright, understood. My question then is: when _do_ we use it? I know of
embedded questions, such as:

> 何を買ったか知っている？
>
> "do you know what they bought"

But I'm not interested in those. I know of 何か and 誰か as distinct words, but
I'm not interested in those either. I think I've heard things like:

> あの女の子が僕を好きなのかと思ったけど

Where the か is in a quoted clause, and I am interested in those, as well as
things like:

> できるか

Which I understand can mean something like "as if I could do it".

Basically, besides embedded questions, when might we actually use か in casual
speech?

Edit: although sundowner's answer is helpful, I'd also like to hear maybe a
more informal description, with examples, of when casual questions use か,
since sundowner's answer only says that questions can take か.




OK, foreigners' grammar does not seem to focus much on each particle per se.
This is more or less a translation of the dictionary definition linked in the
comment.

Sentence-ending か could mean:

  1. Question marker
  2. Question marker, with implied negative.

  * どうしてそんなことしなければならないのか Why on earth do I have to do it (I don't think I have to).

  3. When denying the interlocutor's assumption

  * そんなこと知るか How am I supposed to know that (= I don't know!)

  4. Let's

  * ご飯食べようか Let's eat

  5. Urging (mostly appears as ないか)

  * さっさと宿題やらないか Why not start working on your homework (The speaker is urging to do the homework)

  6. Surprise, exclamation.

  * 誰かと思ったら君だったか I was wondering who it was, and ah, it was you.

The distinction between 2 and 3 is a bit fuzzy.

か in かとおもう is still a question marker, but practically it means _maybe_. E.g.
your sentence means _I thought maybe the girl liked me, but_.

できるか could be a simple question (rising tone) or means 3 (decreasing tone,
usually stressed). Particularly in a manga, it is a common scene where A tells
B to do something impossible and B says できるか!, which means _How could I?_

* * *

Hopefully the following clarifies your question.

Consider the following

  1. きのう何を食べましたか？
  2. きのう何（を）食べました？
  3. きのう何（を）食べた？
  4. きのう何を食べたか？

As you say in the comment, 4 is weird. But note 2 is possible in ます form. Also
in 2 and 3, を tends to be omitted, which is possible in 1 as well.

On the other hand, all of the following are possible.

  5. きのう学校に行きましたか？
  6. きのう学校に行きました？
  7. きのう学校に行った？
  8. きのう学校に行ったか？

5-7 are common with decreasing politeness. 8 is possible, but sounds strongly
masculine, like from someone superior in some sense. I don't know a proper
English word, but in this case for example a father can say 8 to his child.

One possible explanation is that non-ます-form + か sounds masculine, and in case
of wh-question like 4, it sounds almost military. For example, an officer
could say to subordinates この非常事態を何と心得ているか _What do you think of this
emergency?_




OK, foreigners' grammar does not seem to focus much on each particle per se.
This is more or less a translation of the dictionary definition linked in the
comment.

Sentence-ending か could mean:

  1. Question marker
  2. Question marker, with implied negative.

  * どうしてそんなことしなければならないのか Why on earth do I have to do it (I don't think I have to).

  3. When denying the interlocutor's assumption

  * そんなこと知るか How am I supposed to know that (= I don't know!)

  4. Let's

  * ご飯食べようか Let's eat

  5. Urging (mostly appears as ないか)

  * さっさと宿題やらないか Why not start working on your homework (The speaker is urging to do the homework)

  6. Surprise, exclamation.

  * 誰かと思ったら君だったか I was wondering who it was, and ah, it was you.

The distinction between 2 and 3 is a bit fuzzy.

か in かとおもう is still a question marker, but practically it means _maybe_. E.g.
your sentence means _I thought maybe the girl liked me, but_.

できるか could be a simple question (rising tone) or means 3 (decreasing tone,
usually stressed). Particularly in a manga, it is a common scene where A tells
B to do something impossible and B says できるか!, which means _How could I?_

* * *

Hopefully the following clarifies your question.

Consider the following

  1. きのう何を食べましたか？
  2. きのう何（を）食べました？
  3. きのう何（を）食べた？
  4. きのう何を食べたか？

As you say in the comment, 4 is weird. But note 2 is possible in ます form. Also
in 2 and 3, を tends to be omitted, which is possible in 1 as well.

On the other hand, all of the following are possible.

  5. きのう学校に行きましたか？
  6. きのう学校に行きました？
  7. きのう学校に行った？
  8. きのう学校に行ったか？

5-7 are common with decreasing politeness. 8 is possible, but sounds strongly
masculine, like from someone superior in some sense. I don't know a proper
English word, but in this case for example a father can say 8 to his child.

One possible explanation is that non-ます-form + か sounds masculine, and in case
of wh-question like 4, it sounds almost military. For example, an officer
could say to subordinates この非常事態を何と心得ているか _What do you think of this
emergency?_

