Breakdown of Почему ты слез с дивана?
ты
you (singular)
почему
why
диван
sofa, couch
с
off / down from (a surface)
Questions & Answers about Почему ты слез с дивана?
Why do we use the preposition с here instead of из for "from"?
The preposition с (off of / from) is the direct counterpart to на (on). Because you sit on a sofa (на диване), you must use с + Genitive to talk about getting off it. You would use из (out of) if you were leaving the inside of something, which is the counterpart to в (in).
Is it a coincidence that the verb слез starts with the same letter as the preposition с?
Not at all! Russian verbs of motion frequently use a prefix that matches the preposition to reinforce the direction of the movement. The prefix с- on the verb adds the meaning of "down from" or "off of", pairing perfectly with the preposition с.
What is the infinitive of слез, and what does it literally mean?
The infinitive is слезть (perfective). It is built from the base verb лезть (to climb) plus the с- prefix (down/off). While it literally means "to climb down", Russians use it naturally for getting off things you were situated on top of, like a sofa, a bicycle, or a horse.
Why does the word дивана end in "-а"?