Breakdown of Чёрный дым идёт через трубу на крыше.
чёрный
black
на
on, at / by (transport) / to (a place) / to (in answer to)
идти
to go (on foot) / to proceed, go (of a process)
через
through
Questions & Answers about Чёрный дым идёт через трубу на крыше.
Why do we use через трубу instead of сквозь трубу if both mean "through"?
Через is the most common preposition for moving from one side to another or passing through an open channel (like a pipe or a door). Сквозь implies overcoming a physical obstacle or pushing through a dense medium (like squeezing through a thick crowd or water seeping through fabric). Since the pipe is an open channel meant for the smoke, через is the natural choice.
What case is трубу in, and why?
It is in the Accusative case (the feminine noun труба changes its ending to -у). The preposition через always requires the Accusative case when describing the path, space, or medium being crossed.
Why do we use the verb идёт for smoke?
In Russian, the unidirectional verb of motion идти (to go/walk) is used for things that flow, fall, or move steadily in one direction. Just like precipitation "walks" (идёт дождь means "it is raining"), smoke also "walks" out of a chimney.
Why is на крыше in the Prepositional case? Doesn't a verb of motion like идёт usually trigger the Accusative case for the destination?
That is a great catch! While the smoke is moving, на крыше (on the roof) does not describe the destination of the smoke. Instead, it describes the static location of the pipe itself. Because it answers "where is the pipe?" rather than "where is the smoke going?", we use the Prepositional case.