"What does he turn on?"
Translation:Il allume quoi ?
There's no logical grammatical reason for it, but the french language doesn't like to have 2 vowel sounds together, so it adds the -t- in between words when you invert a verb that ends in a vowel and il/elle/on to form a question. For instance, you say "a-t-il" instead of "a-il".
It's the same reason you use contractions of la/le when the following word starts with a vowel, or use a liaison with the preceeding word when a word starts with a vowel. French speakers just think it sounds better and think it sounds funny if you don't have it. The poster comparing it to "an apple" vs "a apple" in English draws a good comparison.
Hi Hivemindx. In french, there are 4 valid ways to ask the question. 1. Qu'est-ce qu'il allume? (La plus classique) 2.Qu'allume-t-il? (Very natural but to be considered a shortened form, for colloquial convenience, just as asking "Que fais tu?/Que dit-elle?Qu'en penses-tu?...) 3. Il allume quoi? (Very familiar and direct, "impulsive" way to talk, imo) 4.Quoi est-ce qu'il allume? ("que" from the application nr1 becomes "quoi", getting the emphasis). // The other two, proposed in the comments, are wrong. I'll tell you why. 1. Allume-t-il quoi? No, bc. in french you cannot have inversion and still put "quoi" at the end. 2. Quoi allume-t-il? No, bc "quoi" as an interrogative pronoun can be put at the beginning only in some definite cases: a)"DE quoi" parle-t-il? À quoi y penser?(with prep), b) Quoi DE neuf?Quoi de plus? (with 'de' and adj. without a verb), c) Quoi faire? (quoi+ infinitive). Sorry for the length of my post. Bonne journée!