At B1 you learned that que covers most cases. At C2 the question is different: when does que stop being enough, and what does choosing something else signal about register?
El cual, la cual, los cuales, las cuales are formal. They become genuinely useful — sometimes obligatory — after a long or compound preposition, where bare que would be unclear or ungrammatical.
| Context | Example |
|---|---|
| after a compound preposition | La razón por la cual vine. |
| after detrás de, a través de… | La ventana a través de la cual miraba. |
| to avoid ambiguity | La hermana de Juan, la cual vive en Lima… |
| non-defining, formal | El informe, el cual fue aprobado ayer… |
With short prepositions (a, de, en, con) the lighter el que is commoner and sounds less stiff: la casa en la que vivo.
The disambiguation trick. In La hermana de Juan, que vive en Lima, who lives in Lima — the sister or Juan? Swapping in la cual forces agreement with la hermana and resolves it. That's the real reason the form survives.
When the relative refers not to a noun but to everything just said, you need the neuter form.
Lo cual only works in non-defining clauses, after a comma. Lo que works in both, which makes it the safer default.
Cuyo agrees with the thing possessed, never the owner. It belongs to written and formal registers; in speech people usually rephrase with de quien or split the sentence.
Cuyo is never interrogative. "Whose is this?" is ¿De quién es esto? — never ¿Cuyo es esto? Using cuyo as a question word is a mistake no native speaker makes, and an easy one for learners to invent.
Quien can open a clause with no antecedent at all, meaning "the one who". It's proverbial and literary.
1.La razón por la ___ vine es muy simple.
2.Llegó tarde, ___ me molestó mucho.
3.El autor ___ novela leímos vendrá mañana.
4.Which is correct for "Whose is this?"
5.Una empresa ___ beneficios han caído un 20%.
6.Fue él ___ lo propuso, no yo.
7.Which form works in BOTH defining and non-defining clauses?
8.La ventana a través de la ___ miraba estaba rota.
9.Cuyo agrees with:
10.No contestó, ___ me pareció muy extraño.
11.Which register does "el cual" belong to?
12.___ mucho abarca, poco aprieta.
Book a class with Ángel and polish your written Spanish — these structures are what formal registers run on.