Relative clauses: kiu, kiun, kiuj, kio

Relative clauses: kiu, kiun, kiuj

Kiu stands in for a noun and does a job inside its own clause. The noun la viro is the subject of every main sentence below, and that makes no difference to kiu:

The -j comes from outside, the -n from inside. Kiu agrees in number with the noun it points back at, and takes its case from its own verb:

Prepositions go in front, never at the end. English strands them; Esperanto has nowhere to strand them to:

• la domo, en kiu mi loĝas - the house I live in
• la ĉambro, en kiun li iris - the room he went into (direction, so -n)

kio and kies

Kio is for when there is no noun to point back at: after tio, ĉio, io or nenio, or pointing at a whole clause.

English uses which for a noun and for a whole clause; Esperanto splits them, kiu for the noun and kio for the clause. Correlatives in prose has the full tio, kio family.

Kies means whose and never takes -j or -n:

• La viro, kies filo venis, estas mia amiko. - The man whose son came is my friend.

The commas

By convention a comma goes before every subordinate clause, and on both sides when the clause sits in the middle:

• Mi scias, ke vi venos. - comma before ke, where English puts none.
• La viro, kiu venis, estas mia frato. - commas at both ends.
• Kiam li venis, ni manĝis. - a clause that comes first is closed by one.

English uses commas to tell a defining clause (the man who came) from an added one (my brother, who came). Esperanto punctuation does not make that split: both take commas. PMEG treats this as convention rather than rule; orthography and punctuation has the detail.