Breakdown of Стоило пожарному взять шланг, как пошла вода.
вода
water
взять
to take / to adopt
пойти
to go (perfective, on foot) / to start (of rain, snow)
как
than (in 'no sooner ... than')
Questions & Answers about Стоило пожарному взять шланг, как пошла вода.
Why is пожарному in the dative case here?
This is the core of the immediate trigger construction taught in this lesson. The word стоило acts as an impersonal verb in this structure, so the logical subject performing the action (the firefighter) must be in the dative case.
Why do we use как here instead of то or и?
In the стоило... как... (no sooner had... than...) structure, как acts as the specific connector showing immediate consequence. You can think of it as meaning 'when suddenly' or 'and immediately' in this pattern, linking the trigger to the instant result.
Why are both verbs (взять and пошла) in the perfective aspect?
The стоило... как... construction emphasizes a rapid chain of events where one completed action immediately triggers another. Because both actions are single, completed events, you must use the perfective aspect for both the infinitive (взять) and the past tense verb (пошла).
Why does the noun for firefighter (пожарный) have an adjectival ending (-ому) here?
The word пожарный is a substantivized adjective. This means it functions completely as a noun (a firefighter), but it keeps the declension endings of an adjective. Therefore, in the dative case, it takes the standard adjective ending -ому.