Interrogatives are questions.
There are four ways of forming French interrogatives.
Do you speak French?
• Vous parlez français?
All that changes here is raising of the voice at the end of a statement. When speaking, intonation is incredibly important, so in this case just changing the tone of your voice indicates a question. This is one of the simplest ways to make a question.
• Parlez-vous français?
Another common question form is to invert the verb (parlez) and the subject (vous), as in parlez-vous?
A hyphen is used between the verb and the subject.
An extra –t- is added between the verb and the pronoun when the verb ends in an -a or -e.
e.g. Parle-t-elle français? - Does she speak French?
Also, in the plural, the t must be pronounced:
Parlent-ils français? - Do they speak French?
(Normally, the –ent would be silent, but in the inverted question form, the t is pronounced).
In the simple past tense (passé compose), it is the avoir or être verb that is inverted, not the past participle.
A-t-il habité en France? - Did he live in France?
As-tu reçu la lettre? - Did you receive the letter?
• Est-ce que vous parlez français?
Est-ce que is a phrase used in front of a sentence to make it a question, the same way we use “Do” in English. Note the word order stays as normal.
• Vous parlez français, n’est-ce pas?
Add the tag n'est-ce pas? to the end of the sentence. It is like the negative - isn't it?, doesn't it? in English.
French Interrogative vocabulary - using question words.
You can also ask questions by using French interrogative vocabulary. Remember to invert the verb and the subject:
Où - Where?
Où est la bibliothèque? - Where is the library?
Quand? - When?
Quand as-tu reçu la lettre? - When did you receive the letter?
Comment? - How?
Comment voyage-t-elle aux Etats-Unis? - How is she going to travel to the U.S.?
Pourquoi? - Why?
Pourquoi est-ce qu’il pleure? - Why is he crying?
Combien? - How much?
Combien coûte-t-il? - How much does it cost?
Combien de? - How many?
Combien d’enfants avez-vous? - How many children do you have?
Que? / Qu'est-ce que? = What? (as the subject)
Que as-tu fait? / Qu'est-ce que tu as fait? - What have you done?
Quel (m.sing.)/Quels (m.pl.)/Quelle (f.sing.)/Quelle (f.pl.) + noun - What? Which?
Note that quel agrees in gender and number with the noun that follows it.
Quel docteur? - What/which doctor?
Quelle voiture? - What/which car?
Qui? / Qui est-ce qui? - Who?
Qui a dit cela? / Qui est-ce qui a dit cela? - Who said that?
Qui? / Qui est-ce que? - Whom
Qui as-tu vu? / Qui est-ce que tu as vu? - Whom did you see?
More grammar help like French interrogatives