Two sentences become one
A relative clause attaches to a noun, the antecedent (antécédent), and says something more about it. The relative pronoun stands right after it and can never be left out. French does not split who from which either: person or thing, masculine or feminine, singular or plural makes no difference.
Two into one
Same noun, two roles
qui - the noun does the action
Le professeur qui explique la grammaire est très patient.
The teacher who explains the grammar is very patient.
que - someone else does the action
Le professeur que nous avons rencontré est très patient.
The teacher we met is very patient.
qui - the subject of the relative clause
The clause has no subject of its own, so the verb follows directly. Only ne or an object pronoun can come in between: qui ne parle pas, qui m'aide. The verb agrees with the antecedent. Before a vowel qui stays unchanged: la personne qui arrive.
qui in sentences
Le bus qui va au centre-ville passe toutes les dix minutes.
The bus that goes to the city centre comes every ten minutes.
J'ai une voisine qui joue du piano tous les soirs.
I have a neighbour who plays the piano every evening.
Ce sont les étudiants qui ont réussi l'examen.
Those are the students who passed the exam.
J'ai un collègue qui ne parle pas anglais.
I have a colleague who doesn't speak English.
que - the direct object
The clause has its own subject, right after que. English deletes the object pronoun all the time (the book I read), French cannot: if you could slip that into the English sentence, French must have que.
que in sentences
Le livre que tu m'as prêté est passionnant.
The book you lent me is gripping.
La chanson que j'écoute vient du Sénégal.
The song I'm listening to comes from Senegal.
L'ami que tu as rencontré hier travaille avec moi.
The friend you met yesterday works with me.
ce qui and ce que - when no noun comes before
When the clause refers to nothing in particular, or to a whole idea, French puts ce in front. The choice is the same: ce qui + verb, ce que + subject. English says what for both, so run the test yourself.
ce qui and ce que in sentences
Je ne comprends pas ce qui se passe.
I don't understand what is happening.
Dis-moi ce que tu veux manger.
Tell me what you want to eat.
Il est arrivé en retard, ce qui a énervé tout le monde.
He arrived late, which annoyed everyone.
J'ai fait tout ce que j'ai pu.
I did everything I could.
