Fuse two short sentences into one smooth idea — que, quien, lo que — out loud.
Your default is que, for people and things alike: el libro que leí, la chica que vive al lado — no accent, ever, in a relative clause. After a preposition, people take quien (la persona con quien hablé, el profesor a quien admiro) or el que / la que (la razón por la que vine, la casa en la que crecí). For an abstract 'what' — an idea, not a noun — use lo que: no entiendo lo que dices. Places take donde (la ciudad donde nací), and cuyo means whose, agreeing with the thing possessed: el autor cuyo libro leí.
Below: the clauses that do the linking, how locals really thread sentences together, the mistakes that tangle them — and how &Be trains this by conversation, not by rewriting sentences on a worksheet.
Say this
Regional Spanish
Textbooks teach one word. Locals use several — pick your region's and stay consistent.
Watch out
The part no drill site can do
Carla
Your grammar teacher for this pack
No sentence-rewriting drills — in the Missing Link lessons, Carla hands you two short, choppy sentences and you fuse them into one smooth clause with que, quien or donde, out loud, mid-conversation. Then she gets you talking about yourself in the abstract — Lo que me gusta de..., Lo que no entiendo es... — and stretches you into the preposition patterns: la razón por la que..., la persona con quien..., el lugar al que... — one of each, in your own words.
Blank mid-sentence and nothing bad happens — she waits. That's the practice, without unnecessary judgement.
Quick answers
Que links back to a specific noun: la película que vimos anoche. Lo que stands for an abstract idea or a whole situation: no entiendo lo que dices, lo que más me gusta es leer. If the 'what' has no noun behind it, you need lo que.
For people, especially after prepositions: la persona con quien hablé, la chica de quien te hablé, la persona para quien trabajo. The classic English-speaker error is la chica que hablé a — Spanish puts the preposition first and switches to con quien or con la que.
No. It's el libro que leí — the accented qué belongs to questions. Writing el libro qué leí is a very common giveaway.
Cuyo means whose and agrees with the thing possessed, not the owner: la mujer cuyos hijos estudian aquí (not cuya hijos). It's mostly for reading and formal writing — in speech people work around it.
La razón por la que vine — literally 'the reason for which I came'. It's the same preposition + el/la que pattern as el restaurante en el que cenamos or los chicos con los que estudio.