Lesson 13: Questions with か and の, featuring のだ
Questions in japanese are usually formed with tone of voice, or with か, or with の. This covers yes/no questions. We'll cover "wh"-questions later.
When a writer has a character ask a question with just tone of voice, they usually use a ？, but otherwise, the ？ is not needed. Japanese doesn't have the same writing rules as english.
熱い？ Is it hot?
When a question is formed with か, the か just goes at the end of the sentence. If the sentence ended with だ (the copula), the だ is removed. There's no special reason for this rule, in fact it can be ignored in archaic writing, it just makes the language simpler.
お前は警察か Are you with the police?
熱いか Is it hot?
知るか？ Do you know?
To frame a question politely, you can use ですか or ますか. ますか is only used with verbs, and it's just the question marker か stuck to a polite verb. ですか attaches to the question you want to ask as a whole, even if it ended with a verb or い-adjective.
彼は学生ですか。 Is he a student?
古いですか Is it old?
来るですか Is it coming?
食べますか Won't you eat?
Sometimes か forms things that look like rhetorical questions, since they're not really looking for an answer. But they're not actually rhetorical, because they're not trying to make a point. Every language does this.
あら、そうか。 Oh, is that so.
I'm not saying that か can't be used for rhetorical questions. It can. It's just that this kind of question isn't necessarily rhetorical.
の acts just like か, except that for nouns, you replace だ with な instead of deleting だ. This is the same な from な-adjectives.
普通なの Is it normal?
食べないの？ Won't you eat?
どうしたの What's wrong?
Answering a の-questions usually uses a のだ-statement or a の-statement. This kind of statement can also stand alone, as a kind of non-comprehensive reason or explanation of something. のだ can be pronounced んだ.
食べたくないのよ I don't really want to eat. (That's why I'm not eating.)
遅いんだ I'm late. (I gotta hurry.)
何してるのだ What are you doing?
何をしてんだ What're you doing?
のだ isn't used when the speaker is merely making a statement. Also, のだ is sometimes a question, but it's rare, and it's always obvious when it is.