Breakdown of Когда ей нужно заплатить штраф? В пятницу.
ей
to her
в
on / during (a time period)
когда
when
пятница
Friday
Questions & Answers about Когда ей нужно заплатить штраф? В пятницу.
Why do we use ей instead of она in this sentence?
In Russian, expressing 'need' often works differently than in English. Instead of saying 'She needs', the literal structure is 'To her it is necessary'. Words like нужно or надо are impersonal, so the person who needs to do the action must be in the Dative case. Ей is the Dative form of она (she).
Why is the verb заплатить used here instead of платить?
Заплатить is the perfective form of the verb 'to pay'. We use it here because she needs to complete a single, specific action—paying this particular fine. If the sentence were about a regular, repeated habit, like paying bills every month, we would use the imperfective verb платить.
What case is the word штраф?
It is in the Accusative case because it is the direct object of the verb (the thing being paid). Since штраф (fine) is an inanimate masculine noun, its Accusative form looks exactly the same as its basic Nominative dictionary form.
Why does пятница (Friday) change to пятницу in the answer?
To say 'on' a specific day of the week, Russian uses the preposition в followed by the Accusative case. Since пятница is a feminine noun ending in -а, its ending changes to -у in the Accusative case, making it в пятницу.