Ce qui retarde le train, c'est la grève.

Question

Hi, in this context below, why is ce qui used instead of qui, when is refers only to a noun which is la grève? ________ retarde le train, c'est la grève. What delays the train is the strike.

Céline Pickard · Accepted Answer

Bonjour Jastine Joyce,
It's important to remember that in French, you cannot start a sentence with the relative pronoun "qui" unless it is a question (in which case, it will be an interrogative pronoun meaning "who"):
Qui retarde le train, c'est la grève = Who delays the train is the strike
Qui a mangé le gâteau ?  = Who ate the cake?
Qui a fermé la porte ? = Who closed the door?
Qui aime la glace à la vanille ? = Who likes vanilla ice cream?
Also, the relative pronoun "qui" is used to refer to something which has already been mentioned in the sentence (i.e an antecedant, which can be a specific person or a thing) and is placed just before "qui".
L'homme qui parle est mon père = The man who is speaking is my father
Le livre qui est sur la table est mon préféré = The book that's on the table is my favourite.
Now, "ce qui" does not refer to a specific person or thing but rather to a fact/an idea. It means "what/which".
Marc n'est pas venu au travail, ce qui est inhabituel = Marc did not come to work which is surprising.
Je ne comprends pas ce qui se passe ! = I don't understand what is going on!
Ce qui te fait peur, c'est d'être seul = What scares you is being alone
I hope this is helpful.
Bonne journée !

Hoang-Long Le · Answer

In my humble comprehension, in "ce qui", ce + S [est]; c' = ce = sujet faux = ce (qui). This style is emphatic. In other words, ce qui retarde le train est la grève. ce qui = pronom indéfini à double fonction which is used for animal, chose, but not person in the singular/plural. For person, animal, chose, la famille [celui qui/que/quoi] in the singular/plural.