Learn Russian: Хотя было поздно, как только дети засмеялись, я улыбнулся. - Although it was late, as soon as the children started laughing, I smiled.

The phrase как только (as soon as) highlights that one action triggers another in a rapid sequence. Because we are focusing on a chain of specific, completed events, we use perfective verbs. Here, the main action (улыбнулся) happened immediately after the condition in the как только clause was met.

Why does the translation say "started laughing"? What does the за- prefix do in засмеялись?

The prefix за- is often added to verbs of sound or motion to indicate the sudden start of an action. While the imperfective verb смеяться means "to laugh" (the ongoing process), the perfective засмеяться specifically means "to start laughing" or "to burst into laughter". This makes it a perfect fit for как только.

Why does the sentence use the neuter form было in было поздно?

This is an impersonal construction, meaning there is no specific grammatical subject (like "he" or "the weather") doing the action. When describing time, weather, or the environment in the past tense, Russian always uses the neuter verb form было paired with an adverb, like поздно (late).

Are all these commas really necessary?