По вечерам мама привычно проверяет, выключен ли газ и закрыта ли форточка.

По вечерам means in the evenings / every evening / evenings generally. It shows a repeated, habitual time.

• вечером = in the evening (often one specific evening, depending on context)
• по вечерам = in the evenings / every evening

So here по вечерам fits well because the sentence describes a regular habit.

Привычно means something like habitually, out of habit, or as usual.

It tells you that the mother checks these things in a routine, automatic way. It is not just that she checks them; she does it as part of an established habit.

A learner should also know that in everyday Russian, people might more often say things like:

• по привычке = out of habit
• как обычно = as usual

But привычно is perfectly understandable and natural in a literary or descriptive style.

The comma separates the main clause from the subordinate clause.

Main clause:

• По вечерам мама привычно проверяет = In the evenings, мама habitually checks

Then comes what she checks:

• выключен ли газ и закрыта ли форточка

This whole part is an indirect question, so Russian sets it off with a comma.

A rough structure is:

• She checks, [whether the gas is off and whether the vent window is closed].

Ли is a particle used to form an indirect yes/no question.

Here:

• выключен ли газ = whether the gas is turned off
• закрыта ли форточка = whether the vent window is closed

So the mother is checking whether one thing is true and whether another thing is true.

This is different from a direct question like:

• Газ выключен? = Is the gas off?
• Форточка закрыта? = Is the vent window closed?

In indirect questions, Russian commonly uses ли.

In Russian, ли usually comes after the word that is in focus.

Here the important thing being checked is the state:

• выключен ли газ = literally something like off-whether the gas is
• закрыта ли форточка = closed-whether the vent window is

The focus is on whether the gas is off and whether the window is closed, so ли follows those words.

You may find this word order unusual if you are thinking in English order, but it is standard in Russian indirect yes/no questions.

They agree with the nouns they describe.

• газ is masculine singular, so: выключен
• форточка is feminine singular, so: закрыта

These are short-form passive participles/adjectival forms used predicatively, roughly like English is turned off / is closed.

Compare:

• газ выключен
• дверь закрыта
• окно открыто
• лампы выключены

The ending changes according to gender and number.

They are short predicative forms, traditionally described as short-form passive participles in many contexts.

In practical learning terms, it is often easiest to understand them as forms used to describe a resulting state:

• выключен = turned off
• закрыта = closed

They are very common after an implied or explicit is/are:

• Газ выключен.
• Дверь закрыта.

Russian often uses these short forms where English uses be + past participle.

Because the sentence describes a habitual, repeated action.

Проверять is the imperfective verb, and it is the normal choice for:

• repeated actions
• ongoing processes
• general habits

Since по вечерам already suggests a routine, проверяет fits perfectly.

If you used the perfective проверит, it would usually refer to one completed future act:

• вечером мама проверит... = this evening mother will check...

Because this sentence checks the current state, not the earlier action.

• выключен ли газ = whether the gas is off
• выключила ли газ = whether someone turned off the gas

The first focuses on the present result. The second focuses on whether the action happened.

In many real situations, Russian prefers the state when the practical concern is the result:

• Is it off?
• Is it closed?

That is exactly what this sentence does.

Yes, газ literally means gas, but in this kind of context it usually refers to the gas supply or the gas stove/burner being left on.

So выключен ли газ means something like:

• whether the gas is turned off
• whether the gas has been shut off
• whether the stove gas is off

The exact English wording depends on context, but in Russian this is a very normal way to say it.

Форточка is not just any window. It usually means a small vent window, little hinged pane, or small opening section of a window used for ventilation.

This is a very common word in Russian-speaking contexts, especially in older-style windows where a small upper section can be opened separately.

So закрыта ли форточка is more specific than simply whether the window is closed.

It is repeated because there are really two separate indirect yes/no questions joined by и:

• whether the gas is off
• and whether the vent window is closed

Repeating ли is normal and clear. It marks both parts explicitly.

Without repeating it, the sentence would sound less balanced and less standard.

The word order is fairly natural as written, but Russian word order is flexible.

This version is neutral and smooth:

• По вечерам мама привычно проверяет, выключен ли газ и закрыта ли форточка.

You could move some elements for emphasis, for example:

• Мама по вечерам привычно проверяет...
• Привычно мама по вечерам проверяет... (more marked)
• Выключен ли газ и закрыта ли форточка, мама по вечерам привычно проверяет would sound very literary or unusual.

So yes, word order can change, but the original is a good standard pattern for learners.

The subject мама belongs to the main clause only:

• мама проверяет

Inside the subordinate clause, the subjects are:

• газ
• форточка

Russian does not need to repeat a verb like is in the subordinate clause, because it is understood through the short forms:

• газ [есть] выключен
• форточка [есть] закрыта

So the sentence is already compact in a very natural Russian way.

It is mostly normal Russian, but привычно gives it a slightly more descriptive or literary feel.

The rest is very ordinary:

• по вечерам
• проверяет
• выключен ли...
• закрыта ли...

In very everyday speech, someone might say:

• По вечерам мама обычно проверяет, выключен ли газ и закрыта ли форточка.
• По вечерам мама проверяет, выключен ли газ и закрыта ли форточка.

So the sentence is natural, but a bit polished in style.