Мне нужно дошить рукав рубашки до вечера.

Because the pattern кому-то нужно + infinitive is a very common Russian way to say that someone needs to do something.

• мне = to me / for me
• нужно = necessary / needed
• дошить = to finish sewing

So Мне нужно дошить... literally feels like To me it is necessary to finish sewing..., which in natural English is I need to finish sewing...

This is why Russian uses the dative here instead of a nominative subject like я.

Russian often uses an impersonal construction here instead of a personal one.

Instead of saying something like Я должна... or Я должен..., Russian commonly says:

• Мне нужно...
• Мне надо...

That means the sentence is built around need/necessity, not around an explicit subject.

So even though English says I need to..., Russian often says To me it is necessary to...

Нужно means necessary / needed and is often translated as need to in sentences like this.

In this structure:

• Мне нужно сделать это = I need to do this
• Ему нужно уйти = He needs to leave

It is a very standard, neutral way to express necessity.

A close synonym is надо:

• Мне нужно дошить рукав...
• Мне надо дошить рукав...

Both are natural. Нужно can sound slightly more neutral or formal, while надо is often a bit more conversational, but in many everyday contexts they are interchangeable.

The base verb is шить = to sew.

The prefix до- often gives the idea of finishing something, doing something to the end, or completing what was left unfinished.

So:

• шить = to sew
• дошить = to finish sewing / sew the rest / complete the sewing

In this sentence, дошить рукав рубашки suggests that the sleeve is not fully finished yet, and the speaker needs to complete that remaining work.

Because the sentence is about a single completed result that must be achieved by a deadline.

Perfective verbs in Russian are used when the focus is on:

• completion
• result
• a one-time finished action

Here, до вечера gives a deadline, and the idea is not just to be sewing, but to finish sewing the sleeve by evening. That makes the perfective дошить the natural choice.

If you used the imperfective дошивать, it would usually describe process, repetition, or background context, not the simple goal of completion.

Because рукав is the direct object of дошить, and рубашки shows possession: the sleeve of the shirt.

Breakdown:

• дошить что? → рукав
• рукав чего? → рубашки

So:

• рукав is accusative singular
• рубашки is genitive singular

A very important detail: рукав is an inanimate masculine noun, so in the singular, its accusative form looks exactly like the nominative:

• nominative: рукав
• accusative: рукав

That is why it does not visibly change here.

Because Russian often uses the genitive to express of relationships.

So:

• рукав рубашки = the sleeve of the shirt

This is a normal noun-noun pattern in Russian:

• дверь дома = the door of the house
• крыша машины = the roof of the car
• рукав рубашки = the sleeve of the shirt

English often uses of or a possessive structure, but Russian usually just puts the second noun into the genitive.

Russian has no articles like a/an/the.

So рукав can mean:

• a sleeve
• the sleeve

The exact meaning depends on context.

In this sentence, because it is рукав рубашки and the situation is specific, English will usually translate it as the sleeve of the shirt or a shirt sleeve, depending on context.

It can suggest either until evening or by evening, but in this sentence the most natural meaning is by evening.

Why? Because the sentence is about completing an action:

• Мне нужно дошить рукав рубашки до вечера.
• The idea is that the finishing must happen no later than evening.

So in English, the best natural translation is usually by evening or before evening.

Grammar:

• до
  • genitive = up to / until / before
• вечера is genitive singular of вечер

Because the preposition до requires the genitive case.

So:

• вечер = evening
• до вечера = until evening / by evening

This is a standard rule:

• до утра = until morning
• до понедельника = until Monday
• до конца недели = until the end of the week

Yes, that is possible, but it is not exactly the same in tone.

Compare:

• Мне нужно дошить рукав рубашки до вечера = I need to finish sewing the shirt sleeve by evening.
• Я должен дошить рукав рубашки до вечера = I must / am supposed to finish sewing the shirt sleeve by evening.

The difference is roughly:

• нужно focuses on necessity or practical need
• должен / должна can sound more like obligation, duty, or expectation

So мне нужно is often softer and more neutral.

Usually not if you mean finish what is already partly sewn.

• сшить usually means to sew/make something completely, often from start to finish
• дошить means to finish sewing something that was already started

So the choice depends on the situation:

• If the sleeve has not been made at all and you mean make/sew the sleeve, сшить might fit better in some contexts.
• If the sleeve is partly done and you need to complete the remaining sewing, дошить is the better verb.

In this sentence, дошить strongly suggests unfinished work that needs to be completed.

No, Russian word order is fairly flexible, although different orders can change emphasis.

Neutral order:

• Мне нужно дошить рукав рубашки до вечера.

Other possible orders:

• Мне нужно до вечера дошить рукав рубашки.
• До вечера мне нужно дошить рукав рубашки.

These are all possible, but the emphasis shifts a little:

• putting до вечера earlier highlights the deadline
• keeping it at the end sounds neutral and natural

So the original sentence is a very normal, unmarked way to say it.

Yes, in this sentence рукав рубашки is more natural.

Russian has two common possession patterns:

• рукав рубашки = the sleeve of the shirt
• рукав у рубашки = the shirt has a sleeve / the sleeve on the shirt

The genitive noun pattern (рукав рубашки) is the standard choice when simply naming a part of something.

The у + genitive pattern is more often used when emphasizing possession or existence in a broader way.

This sentence would not need to change at all:

• Мне нужно дошить рукав рубашки до вечера.

That is because:

• мне does not show gender
• нужно does not show gender
• the infinitive дошить does not show gender

If you used я должен / я должна, then gender would matter:

• male: Я должен дошить...
• female: Я должна дошить...

But with мне нужно, the sentence stays the same for both male and female speakers.