Any sentence can be made into a question by adding nei, but there are other question words that get more specific. Like most things in Reisu there's a pretty simple pattern to it.
|How much, How many||Jei|
|Which, Which one||Zei|
O hola mei?
Translation: How do you feel?
Transliteration: You feel how?
Kata neina zei?
Translation: What time is it?
Transliteration: Time says when?
Fagevo geri jei?
Translation: How much for the blanket?
Transliteration: Blanket(that) costs how much?