Learn Hardcore Russian: Необходимо зарядить устройство полностью до послезавтра. - It’s necessary to charge the device fully by the day after tomorrow.

Необходимо is an impersonal predicate that expresses necessity. In English you’d render it as “it is necessary,” but in Russian there is no explicit subject. The infinitive that follows tells us what exactly must be done.

Why is the verb зарядить in the infinitive form instead of a conjugated form?

After impersonal predicates of necessity like необходимо, Russian requires an infinitive to indicate the needed action. Here зарядить (“to charge”) tells us what you must do to the device.

Why is зарядить perfective, not imperfective like заряжать?

Perfective aspect (зарядить) focuses on completing the action once, which fits a deadline: you need the device fully charged by a certain time. The imperfective заряжать would stress the ongoing process or repetition, not its completion.

Why is устройство in the accusative case?

In Russian, the direct object of an infinitive takes the accusative. Here устройство (device) is what you charge, so it’s marked as the object. Since it’s inanimate, its accusative form looks identical to the nominative.

What part of speech is полностью, and why is it placed after the object?

Полностью is an adverb meaning “completely.” Word order in Russian is flexible, so adverbs can appear before or after objects and verbs. Placing it after устройство emphasizes that the device must reach full charge.

Why do we need the preposition до before послезавтра?

До + a time expression indicates a deadline, “by [that time].” Without до, послезавтра simply means “the day after tomorrow” as a point in time, not a latest permissible moment.

Could you say послезавтра here without до to mean “by the day after tomorrow”?

No. Without до, послезавтра only answers “when?” (positional). To express “you must finish something before or by that time,” you always use до + time noun.

What’s the difference between необходимо and нужно?

Both mean “it is necessary,” but необходимо is more formal or neutral, and often found in written instructions. Нужно is more colloquial and spoken. Grammatically they behave similarly, taking an infinitive.

Is there a subject in this sentence?

No. This is an impersonal construction: necessity is expressed without a subject. The sentence literally says “It is necessary to charge the device…” with no “you” or “we” specified.