Breakdown of Они должны закончить проект к понедельнику.
они
they
понедельник
Monday
проект
the project
должен
must, have to
закончить
to finish (perfective)
к
by (a deadline)
Questions & Answers about Они должны закончить проект к понедельнику.
Why do we use к понедельнику instead of в понедельник?
Using в понедельник means they will finish the project on Monday. The preposition к followed by the Dative case (понедельнику) is used to express a deadline, meaning the project needs to be finished by Monday (and could be completed sooner).
What case is понедельнику and why?
It is in the Dative case. When expressing a deadline meaning "by a certain time," the preposition к always requires the Dative case. For the masculine noun понедельник, this means adding the ending -у.
Could I use им надо or им нужно instead of они должны?
Yes, you could say им нужно закончить or им надо закончить to mean "they need to finish." However, они должны (a short-form adjective agreeing with the Nominative subject они) translates closer to "they must" or "they are obliged to." This is often used to emphasize strict professional deadlines or duties.
Why does закончить have to be a perfective verb here?
Deadlines with к focus entirely on the result: having the task completed by that specific time. Because of this focus on the final result rather than the ongoing process, you will almost always use a perfective verb like закончить rather than its imperfective pair заканчивать.
Is the word проект in the Nominative case here?
It looks like it, but it is actually in the Accusative case because it is the direct object being finished. Because проект is an inanimate masculine noun, its Accusative form is identical to its Nominative form.
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