(1)Interrogative sentences containing question words (QW) can be combined with expressions such as わかりません(I don't know), おしえてください(please tell me), ききました(I asked), and 知っていますか(do you know).
The verb used with QW is in the plain form. The question words introduced thus far include: いつ(when), どこ(where), だれ(who), なに(what), いくら(how much), and どちら(which direction).
(2)It is also possible to put か immediately after the question word and make sentences such as いつか知っていますか(Do you know when it is ?) and どこかわかりません (I don't know where it is.)
パーティーは 何時に はじまりますか。(時間を)おしえて ください。
What time does the party start? Please tell me [the time].
→パーティーは 何時に はじまるか、(時間を)おしえて ください。
Please tell me what time the party starts.
この けんは いくらですか。 父に ねだんを ききました。
How much is this ticket? I asked my father {the price}.
→この けんは いくらか、 父に(ねだんを)ききました。
I asked my father how much this ticket is.