Мой брат вечно теряет ключи из-за своей рассеянности.

In Russian, the present tense is often used for habitual actions—things someone does regularly.

So Мой брат вечно теряет ключи means My brother is always losing his keys / My brother always loses his keys.

Here, теряет is not about one specific moment right now. It describes a repeated pattern.

Теряет is:

• 3rd person singular
• present tense
• from the verb терять = to lose

It matches мой брат because брат is he, singular.

So:

• я теряю = I lose
• ты теряешь = you lose
• он/мой брат теряет = he / my brother loses

Russian uses the imperfective aspect here because the action is repeated or habitual.

• терять = imperfective, used for repeated or ongoing losing
• a perfective verb like потерять would usually point to one completed instance of losing something

So:

• Мой брат вечно теряет ключи = He keeps losing his keys
• Мой брат потерял ключи = He lost the keys

Because the sentence talks about a recurring problem, терять is the natural choice.

Literally, вечно can mean eternally or forever, but in everyday speech it very often means:

• always
• constantly
• all the time

In this sentence, it usually adds a tone of annoyance, complaint, or frustration.

So вечно теряет ключи sounds a bit like:

• He’s always losing his keys
• He keeps losing his keys

It is less neutral than simply всегда.

Ключи is accusative plural here because it is the direct object of теряет.

The basic dictionary form is:

• ключ = key

Plural nominative:

• ключи = keys

For inanimate masculine nouns, the accusative plural is the same as the nominative plural. So:

• ключи can mean either keys as the subject form or keys as the object form, depending on the sentence

In теряет ключи, it is clearly the object: loses keys.

Russian often omits possessives when ownership is obvious from context.

In English, you would usually say his keys, but in Russian that is often unnecessary if the listener naturally understands whose keys they are.

So:

• Мой брат вечно теряет ключи already strongly suggests his own keys

If you wanted to make it explicit, you could say:

• Мой брат вечно теряет свои ключи

That is correct, but the shorter version is very natural.

Свой is the reflexive possessive pronoun in Russian. It refers back to the subject of the clause.

Since the subject is мой брат, Russian normally prefers:

• из-за своей рассеянности = because of his own absent-mindedness

This is more natural than его here.

Why?

Because свой clearly means the absent-mindedness belongs to the subject himself.
Using его is sometimes possible in Russian, but it can sound less natural here and may be less clear in other contexts.

A good rule:

• when the possessor is the subject, Russian often uses свой

The preposition из-за requires the genitive case.

So рассеянность changes to рассеянности, and своя changes to своей.

Base forms:

• своя
• рассеянность

After из-за:

• из-за своей рассеянности

So the structure is:

• из-за
  • genitive
• meaning because of

Examples:

• из-за дождя = because of the rain
• из-за работы = because of work
• из-за своей рассеянности = because of his own absent-mindedness

Here из-за means because of.

So:

• из-за своей рассеянности = because of his absent-mindedness

Be aware that из-за can also have a more literal spatial meaning in other contexts, like from behind, but in this sentence it clearly has the meaning because of.

Also, из-за often introduces a cause, and sometimes the cause is negative or problematic, which fits this sentence well.

Рассеянность is a noun meaning something like:

• absent-mindedness
• scatterbrainedness
• lack of attention
• distraction

It comes from the adjective:

• рассеянный = absent-minded, distracted

So:

• из-за своей рассеянности means because of his absent-mindedness / because he is so absent-minded

Russian word order is flexible, but the original order is very natural and neutral:

• Мой брат вечно теряет ключи из-за своей рассеянности.

This order presents the idea clearly:

1. subject: мой брат
2. frequency/emotional adverb: вечно
3. verb: теряет
4. object: ключи
5. reason: из-за своей рассеянности

You can rearrange parts for emphasis, for example:

• Из-за своей рассеянности мой брат вечно теряет ключи.

This puts more focus on the reason first: Because of his absent-mindedness...

So the meaning stays similar, but the emphasis changes.

Yes, but the tone changes.

• всегда = always, neutral
• вечно = always/constantly, often with irritation or exaggeration

Compare:

• Мой брат всегда теряет ключи.
  More neutral: My brother always loses his keys.

• Мой брат вечно теряет ключи.
  More emotional: My brother is always losing his keys.

So вечно is a very natural choice if the speaker is complaining.

The stress is:

• мой брат
• вЕчно
• терЯет
• ключИ
• из-за
• своЕй
• рассЕянности

So a helpful pronunciation guide is:

мой брат ВЕчно терЯет ключИ из-за своЕй рассЕянности

Pay special attention to:

• терЯет
• ключИ
• рассЕянности

Those stresses may not be obvious to an English speaker.