Eu saí de casa sem que minha irmã desligasse a televisão.

Because sem que normally triggers the subjunctive in Portuguese.

In this sentence, sem que minha irmã desligasse a televisão means something like without my sister turning off the TV. The idea is not being presented as a completed fact, but as something that did not happen before the main action. Portuguese commonly uses the subjunctive after expressions like sem que, because they introduce something uncertain, unrealized, denied, or dependent on another action.

So:

• sem que + subjunctive = without someone doing something

Examples:

• Saí sem que ele me visse. = I left without him seeing me.
• Ela viajou sem que os pais soubessem. = She traveled without her parents knowing.

Because after sem que, you need the subjunctive, and here the sentence is referring to a past situation, so Portuguese uses the imperfect subjunctive: desligasse.

Breakdown:

• desligou = simple past indicative, not correct after sem que
• desligava = imperfect indicative, also not correct here
• desligasse = imperfect subjunctive, which fits the structure

The main verb is saí (I left), which is in the past, so the subordinate verb after sem que usually appears in the imperfect subjunctive.

A useful pattern is:

• Saí sem que ela desligasse...
• Vou sair sem que ela desligue...

Past main verb often leads to imperfect subjunctive in the subordinate clause.

Yes, that is also possible, and it is very natural.

So you can say both:

• Eu saí de casa sem que minha irmã desligasse a televisão.
• Eu saí de casa sem minha irmã desligar a televisão.

The second version uses the personal infinitive: desligar agrees in meaning with minha irmã as the subject.

Very roughly:

• sem que + subjunctive = slightly more explicit, often a bit more formal or structured
• sem + personal infinitive = very common and often a little more direct

Both are correct in Brazilian Portuguese.

In Portuguese, casa often appears without an article when it means home in a general sense.

So:

• saí de casa = I left home
• voltei para casa = I went back home
• estou em casa = I’m at home

But if casa means a specific house, an article is more likely:

• Saí da casa da minha tia. = I left my aunt’s house.

So in your sentence, de casa means from home, not from the house in a specific physical-description sense.

Portuguese uses definite articles much more often than English.

So where English says:

• turn off the TV

Portuguese usually says:

• desligar a televisão

The article a is normal here because Portuguese often uses articles with common nouns, especially when talking about familiar, specific things in context.

Other examples:

• Fechei a porta. = I closed the door.
• Lavei as mãos. = I washed my hands.
• Ele quebrou o celular. = He broke his phone.

English often omits or changes articles in places where Portuguese keeps them.

Because Portuguese often uses possessives where English might also use them, especially for family relationships.

So:

• minha irmã = my sister

You could sometimes omit the possessive if context makes it clear, but that would usually change the sentence or make it sound less natural here. In this sentence, minha irmã clearly identifies whose sister we are talking about.

Also, in Brazilian Portuguese, possessives are very common with family terms:

• meu pai
• minha mãe
• meu irmão
• minha irmã

The accent in saí shows both stress and hiatus.

The verb is sair. In the first-person singular preterite, it becomes saí.

The accent tells you that the vowels are pronounced separately:

• sa-Í not as a single blended sound

So:

• saí = I left
• sai = he/she leaves, or imperative leave!, depending on context

The accent helps distinguish these forms in writing and pronunciation.

No, Eu is optional.

Portuguese often drops subject pronouns when the verb form already makes the subject clear.

So both are correct:

• Eu saí de casa sem que minha irmã desligasse a televisão.
• Saí de casa sem que minha irmã desligasse a televisão.

Because saí clearly means I left, the subject is already obvious.

You include Eu when:

• you want emphasis
• you want contrast
• you want extra clarity

For example:

• Eu saí, mas ela ficou. = I left, but she stayed.

Here, sem que means without followed by a clause with its own subject.

Compare these:

• Saí sem falar. = I left without speaking.
• Saí sem que minha irmã desligasse a televisão. = I left without my sister turning off the TV.

So:

• sem + infinitive = when the action is more general or shares the same subject
• sem que + subjunctive = when you introduce another clause, often with another subject

In your sentence, minha irmã is the subject of the second action, so sem que works very naturally.

Usually, yes, or at least it strongly suggests that turning off the TV was expected, relevant, or desired.

The sentence says that the speaker left home and that the sister had not turned off the television before that happened. This often creates a sense of:

• expectation not fulfilled
• annoyance
• consequence
• unfinished action

But the grammar itself does not explicitly say she should have. That comes more from context and common interpretation.

Yes, depending on context.

Grammatically, the sentence says that the speaker left home and the sister did not turn off the TV before that departure. It does not by itself explain why.

Possible interpretations include:

• she forgot to turn it off
• she refused to turn it off
• she had no chance to turn it off
• the speaker left suddenly

So the sentence focuses on the fact that the action did not happen, not necessarily on the reason.

Saí is the preterite of sair in the first-person singular.

So:

• eu saí = I left / I went out

This tense usually presents the action as completed.

Quick comparison:

• eu saía = I used to leave / I was leaving
• eu saí = I left

In your sentence, saí gives the main completed past event, and desligasse appears in the subordinate clause because of sem que.

Yes, to some extent.

The original order is very natural:

• Eu saí de casa sem que minha irmã desligasse a televisão.

You could also say:

• Sem que minha irmã desligasse a televisão, eu saí de casa.

That version is grammatical, but it sounds more formal or literary because it front-loads the subordinate clause.

In everyday Brazilian Portuguese, the original order is more common and more neutral.