Learn Hardcore Russian: Мой брат зарабатывает в городе, а сестра работает дома. - My brother earns money in the city, and my sister works from home.

А signals a contrast between two coordinated clauses. The most natural English equivalents are “whereas” or “while,” sometimes a mild “but.” It contrasts the brother’s situation with the sister’s without implying conflict. Using и (“and”) would simply add facts with little contrast; но (“but”) would be a stronger, adversative “but.”

Why is there мой before брат but nothing before сестра? Can I say моя сестра?

Russian often omits possessives when the possessor is obvious (family members are a common case). Repeating мой/моя can sound heavy. Here, once “my” is established with мой брат, it’s natural to say just сестра. You can say моя сестра—it’s grammatical and fine if you want to emphasize that she’s your sister too.

What’s the difference between зарабатывает and работает?

зарабатывать = to earn (money), to make a living. It focuses on income.
работать = to work (do a job/activity). It may or may not imply pay. So the brother is specifically earning (in the city), while the sister is working (at home).

Do I need to add деньги after зарабатывает?

No. Зарабатывать implies “earn money” by default, so Он зарабатывает is complete. You can add:

зарабатывает деньги (earns money),
зарабатывает на жизнь (earns a living),
зарабатывает на машину (is saving/earning for a car).

Why is it в городе but дома with no preposition?

в городе uses the preposition в
- the prepositional case to indicate location: “in the city.”
дома is an adverb meaning “at home,” so no preposition is used. Compare:
дома = at home (adverb, general place).
в доме = in the house (inside a specific building).
на дому = at home as a place of work (set phrase for home-based/remote work).

Which case is городе?

Prepositional case (after в for location): город → в городе (“in the city”). Don’t say в городу here—that’s the dative, which is used after по: по городу (“around the city”).

Is дома here the plural “houses”?

No. There are two forms spelled the same:

до́ма (stress on the first syllable) = “at home” (adverb) — that’s the one here: работает до́ма.
домá (stress on the last syllable) = “houses” (nominative plural). Context and stress distinguish them.

Why do both verbs end in -ет (…зарабатывает, …работает)?

They are 3rd person singular present-tense forms (he/she works/earns) of first-conjugation verbs, which typically take -ет/-ёт. Present tense doesn’t mark gender, so both are the same ending. In the past, gender would show: брат зарабатывал, сестра работала.

What about aspect—are these imperfective?

Yes. Зарабатывает and работает are imperfective present, used for ongoing/habitual actions. Perfective partners:

заработать = to earn (successfully, a completed result),
поработать = to work for a while (completed interval). Perfective doesn’t have a true present; its “present” forms refer to the future.

Could I use и instead of а?

Grammatically yes: …, и сестра работает дома. But и merely adds another fact, while а highlights a contrast (“my brother earns in the city, whereas my sister works at home”). Use и if you don’t want to emphasize the difference.

Do I need the comma before а?

Yes. А connects two independent clauses here, so a comma is required: …, а …. This matches standard Russian punctuation rules.

Can I change the word order? For example: Сестра дома работает, а брат в городе зарабатывает.

Yes. Russian word order is flexible. Your version is grammatical; it shifts emphasis:

Original highlights what the brother does first.
Swapping order or moving adverbials (в городе, дома) changes focus or rhythm, but the core meaning stays.

Does в городе mean he lives there or just works there?

It tells you where he earns money, not necessarily where he lives. He could live in the suburbs or a village and commute. To make commuting explicit, you might say Он ездит в город на работу.

Does работает дома mean remote work, or could it mean housework?

By default it suggests working from home (remote work/freelance), but context matters. To emphasize household chores, people often use:

работает по дому (does housework),
занимается домашними делами,
ведёт хозяйство. For formal “home-based employment,” работает на дому is common.

Why is it мой брат (masculine) but would be моя сестра (feminine) if we included the possessive for sister?

Possessive pronouns agree with the noun’s gender:

мой брат (masc.),
моя сестра (fem.),
моё письмо (neut.),
мои дети (plural). In the sentence, моя before сестра is simply omitted for style/avoidance of repetition, not because of grammar.