First, a correction: "est-ce que" comes before yes/no questions. "qu'est-ce que" or "qu'est-ce qui" (depending on if the "what" in the question is the object or subject, respectively) comes before what questions.
It's usually best not to try to directly equate phrasings of one language to phrasings of another. What "est-ce que" really "means" is that "what'...
"De qui parles-tu ?" would be a perfectly normal thing to say to a close friend, even if some would notice the effort on the construction of the sentence. If you want to make it sound really casual, just don't invert the verb and the subject: "De qui tu parles ?". This is an extremely common thing to do in French.
Other examples of transformation from well-...
Does such a thing as question tags exist in French?
Yes, the closest equivalent is "n'est-ce-pas ?" which is much simpler as it stays invariable unlike the English form. However, it is not that much used nowadays and is becoming too formal and quite outdated, at least in France.
— Tu n'a pas mangé, n'est-ce-pas ?
— Si, j'ai mangé.
— Non, je n'...
In formal language, affirmations have subject – verb – object complements order and yes/no questions have verb – subject – object complements order. So,
Vous êtes beau is an affirmation.
Êtes-vous beau ? is a yes/no question.
(If the subject is not already a pronoun, it comes first and a pronoun is added after the verb to form questions. E.g. Pierre est-il ...
Technically, the sentence is missing a comma:
Tu l'as acheté où, ce pantalon ?
To parse it, better to first ignore the trailing part that is optional. That reads:
Tu l'as acheté où ? or the variants où tu l'as acheté ? and où l'as-tu acheté ? (formal)
This clearly translates to
Where did you buy it?
But the person speaking wants to make sure you know ...
You can use the expression tous les combien:
Tous les combien, interroge sur la fréquence : L'autobus passe tous
les combien ?
Note there is no s at the end of combien since the latter is an invariable noun (masculine):
Le combien (nom masculin invariable), indique le quantième du mois, le rang : Le combien
sommes-nous ? Le combien est-il au ...
Short answer: "Où est-ce que ma chaise est ?" is correct.
Long answer: "est-ce que" is used in order to keep the order between the subject and the verb.
For "Ma chaise est là." the following sentences are correct:
"Où est ma chaise ?"
"Où ma chaise est-elle ?"
"Où est-ce que ma chaise est ?" (may ...
As a native I would say :
Où est-ce qu'est ma chaise?
Où est ma chaise?
I think you do not say Où est-ce que ma chaise est? or at least I never hear people using it.
Maybe because it is not a pronom, because Où est-ce qu'elle est? is used.
Maybe because there is nothing behind because Où est-ce que ma chaise est passée? is also used.
I do not know ...
First let's rule out "Est-ce que correct si...", which is obviously... not correct. :)
"Est-ce que je peux..." is the natural way of asking, and the one I would usually use as a native speaker. The use of "pouvoir" really means we are asking for permission here.
Is it ok if I smoke here?
Est-ce que je peux fumer ici ?
As you said though, the ...
“Combien de temps“ is right, but “passe-t-il” is not. The appropriate sentence here is “durer” (“to last”) and your sentence should be “Combien de temps ce film dure-t-il ?“ or “Combien de temps dure ce film ?“.
Note that “Combien de temps dure-t-il ce film ?“ is erroneous as well.
Moreover, while “Combien de temps est-ce que nous y resterons ?” is ...
It's always depend of the language level because "ok" is never used in "correct" or writing form.
Speaking with a friend for a party "Is it ok if I bring my sister ?" will probably be "J'emmène ma soeur, ok ?" (forcing) or "C'est ok si j’amène ma soeur ?" (asking) or "Est-ce que je peux emmener ma soeur ?" (mail/sms).
But to a stranger in front of a ...
Normalement, dans une phrase interrogative il y a inversion du sujet.
Comment devient-il agréable ?
Quand le sujet est complexe, on devrait avoir
*Comment devient un lieu agréable ?
qui ne se dit pas. On laisse le sujet en place, et on utilise un pronom de reprise :
Comment un lieu devient-il agréable ?
L'absence du pronom de reprise n'est pas ...
Il y a plusieurs manières de poser cette question, par exemple :
Le matin, tu te lèves à quelle heure ? (Attention aux accents)
À quelle heure est-ce que tu te lèves le matin ?
À quelle heure te lèves-tu le matin ?
La question 1 est surtout utilisée à l'oral, en langage familier. Par contre, la question 3 est la forme la plus soignée.
Ce ne sont que ...
"Il est quelle heure ?" is correct when you are speaking. I've never seen it in a text (except in written dialogue).
In general, this word order seems to belong to the familiar register, but it's perfectly okay for more formal situations as well (for example, when a boss asks his/her employees). With the other order of words "Quelle heure est-il ?", it ...
There is no good direct translation I can think of, one would rather say “are you doing it often” and depending on the answer ask further “at which frequency”.
Allez-vous souvent à la piscine? (Are you often going to the swimming pool?)
Oui, régulièrement (Yes regularly)
Ah oui? À quelle fréquence ? (Really? How often?)
Deux fois par semaine (Twice ...
Even though this is more or less a duplicate, I'll add an explanation that I didn't see when skimming previous answers.
The subject pronouns are clitics, which have some fascinating properties but are perhaps best summarized as being between words and affixes. They're smaller and less independent than words, but more than affixes.
Now let's see how this ...
I would tend to agree with your characterization of tone as informal (only when speaking anyway), est-ce que being fairly standard/neutral/common these days, and the inversion being more formal - although as you note, there are expressions where the inversion is natural.
At least for the first two examples you give, I would see nothing wrong with the way you ...
The grammatically correct formal sentence would be:
De quel instrument jouez-vous ?
A still grammatical spoken French:
De quel instrument est-ce que vous jouez ?
In non formal, real life, you'll more often hear the casual :
Vous jouez de quel instrument ?
Tu joues (de) quoi comme instrument ?
“Qu'as fait tu ?” is not correct. According to francaisfacile.com (emphasis mine), in questions:
On conjugue un verbe impérativement en plaçant le pronom sujet
a) après le verbe aux temps simples et
b) après l'auxiliaire aux temps composés.
So the correct phrasing is
Qu'as-tu fait ?
And the negation:
Que n'as-tu pas fait ?
They are equivalent in meaning. The form with the subject and verb inverted is more formal.
In general, the order of question formality from most to least looks like this:
Dors-tu ? Que fais-tu ? Fais-tu quelque chose ?
Est-ce que tu dors ? Qu'est-ce que tu fais ? Est-ce que tu fais quelque chose ?
The translation for each would be
pas vrai - no way (when being astonished, not very formal) or right (common)
c'est ça - is that it (common)
n'est-il pas - isn't it (formal)
"Hein" doesn't really have a translation, it's widely used for a lot of things.
But to answer you, there's is no real word to use, they all depend on the context in which you're ...
The idiomatic phrasing is:
Comment se fait-il que … ?
For some reason the clause is usually in the subjunctive mood. In this case:
Comment se fait-il que je sois arrivé avant toi ?
It could however be in the indicative, I suppose, when the fact is more important than the reason.
Comment se fait-il que ces poules ont des dents ?
The verb vouloir can be followed by either a bare infinitive or a noun phrase.
que voudriez-vous boire?
que voudriez-vous manger?
In these sentences, there is no preposition before "boire" and "manger" because they are the complement of the verb vouloir.
Je voudrais quelque chose à boire.
Je voudrais quelque chose à manger.
There are two differences between the proposed constructions:
Using tu or vous
I suppose this is not the problem and won't even stop on this. If this is a problem, I suppose a separate question would be better.
Order of the words
As Casey said, both proposed structures are used but both fall outside of the grammar rule book we learned as children. Below ...
That's kinda broad and you will have several translations depending on what you're asking. In a lot of them, the expression Se Passer would make a great fit. For instance:
How is your day going?
Comment se passe ta journée ?
How are your holidays going on ?
Comment se passent tes/vos vacances ?
It means "What's up?", "What's happening?". Translated literally, it means "what is there?": "il y a" means "there is" and you turn it into a question. In this context, the friend is asking what the other called about, stating that he just left work (explaining why he couldn't answer the phone).
Note that the meaning can change a little depending on the ...