When to use the perfective and imperfective form of розуміти

Question

"Я розумів, або може бути я зрозумів".

I’m having difficulty understanding when to use the perfective form or the imperfective form of розуміти. If Я зрозумів, що він сказав (I understood what he said), did I stop understanding it when he stopped talking?

This has to be the most fun language in the world to study with its nuances and challenges.

Answer 1

Я зрозумів ≈ I have understood. You can do this [understand] only immediately, so it is to finish [understand something, usually all of the thought].

Я розумів ≈ I was understanding. This is understanding while something [are doing] in during time, or you understand something to point of time and after you do not understand for some reason.

Letʼs examples.

Я зрозумів, що він сказав. You understood all after (it can be also after a long time) his talking.

Я розумів, що він сказав. As you see, сказав is not “are doing”, so we take the second part: at least now you do not understand what he said.

For the first part, we must change word сказав to казав: Я зрозумів, що він казав.

1. He was talking and you understand him
2. You already know or understand the theme before of his talking.

Я зрозумів, що він казав.

1. You understood him before he ended talking.
2. Same as with сказав, but with a focus that he talking long.