Мой брат носит документы в офис каждый день, а сегодня я несу туда только одну папку.

Because Russian distinguishes between two related verbs for carrying:

• нести = to carry in one specific direction, often right now
• носить = to carry habitually, repeatedly, or in different directions

So:

• Мой брат носит документы в офис каждый день = he does this regularly, every day
• сегодня я несу туда только одну папку = today I am carrying one folder there, a specific trip

This is a very common Russian pattern with verbs of motion.

Not in the usual perfective/imperfective sense. They are both generally treated as imperfective, but they differ in directionality:

• нести = determinate / one-direction movement
• носить = indeterminate / repeated, habitual, or multi-directional movement

So the contrast here is not mainly about completed vs. ongoing action. It is about type of movement:

• repeated habit → носит
• one current trip → несу

Because в офис expresses motion toward a destination: into / to the office.

In Russian:

• в + accusative = motion to/into
• в + prepositional = location in/inside

So:

• в офис = to the office
• в офисе = in the office

In this sentence, someone is carrying things to the office, so в офис is correct.

Because каждый день is a fixed and very common way to say every day in Russian.

Here:

• каждый = every
• день = day

The phrase uses the accusative singular form:

• masculine inanimate день looks the same in nominative and accusative
• каждый agrees with it

So каждый день literally looks like every day, with no preposition needed.

They are different objects:

• документы = documents
• одну папку = one folder

The sentence says that the brother regularly carries documents to the office, but today the speaker is carrying only one folder there.

So there is no grammar problem here—just a change in what is being carried.

Because папку is the direct object of несу, so it must be in the accusative case.

Папка is feminine, so:

• nominative: одна папка
• accusative: одну папку

Both the numeral/adjective одна → одну and the noun папка → папку change.

This is a very important pattern for feminine nouns in -а.

It actually is in the accusative plural, but for inanimate masculine nouns, the accusative plural is usually the same as the nominative plural.

So:

• nominative plural: документы
• accusative plural: документы

Since документы is the direct object of носит, it is accusative here, even though it looks unchanged.

Туда means there, but specifically to there / to that place.

It is used for motion toward a destination, not simple location.

So:

• там = there (location)
• туда = to there / thereward, toward that place

In this sentence, туда refers back to в офис from the first clause. So the second clause avoids repeating в офис and instead says there:

• а сегодня я несу туда только одну папку = but today I’m carrying only one folder there

Because а often marks a contrast or a shift of topic, while и usually just means and.

Here the contrast is:

• my brother does this every day
• but today I am carrying only one folder there

So а works well because the sentence is comparing two situations:

• different person: брат vs я
• different pattern: habitual vs. today’s specific action
• different object: documents vs. one folder

In English, this а is often translated as and, while, or but, depending on context.

Yes, Russian often omits subject pronouns when they are clear from the verb form. So несу already tells us I carry / I am carrying.

However, я is included here for emphasis or contrast:

• мой брат ...
• а сегодня я ...

This makes the contrast clearer: my brother vs. I.

So the pronoun is not strictly necessary, but it sounds natural and useful here.

They help signal two different kinds of action:

• каждый день = repeated, habitual action → носит
• сегодня = a specific occasion, today’s trip → несу

These time expressions strongly support the distinction between the two carrying verbs. A Russian learner should get used to noticing this pattern:

• habitual/repeated → often носить
• one current trip in one direction → often нести

Russian word order is fairly flexible, but this version is very natural.

Current order:

• Мой брат носит документы в офис каждый день, а сегодня я несу туда только одну папку.

This order works well because it presents information clearly:

1. who does it
2. what he carries
3. where
4. how often
5. contrast with today
6. who is acting now
7. where
8. what exactly is being carried

Some parts could move for emphasis, for example:

• Сегодня я несу туда только одну папку
• Я сегодня несу туда только одну папку

But the original sentence is a normal, natural way to say it.

Yes. In context, несу often corresponds to English am carrying, because it refers to a specific action in progress or a current trip.

So:

• сегодня я несу туда только одну папку

could be understood as:

• today I’m carrying only one folder there
• or today I’m taking only one folder there

English and Russian do not match perfectly here, but am carrying is a very natural translation in this context.