После ужина мы открыли один гранат и долго ели его всей семьёй.

Because после always takes the genitive case.

• ужин = dinner
• после ужина = after dinner

So ужина is the genitive singular form of ужин.

This is a very common pattern:

• после урока = after the lesson
• после работы = after work
• после фильма = after the film

Открыли is perfective past tense, so it presents the action as a completed whole: we opened it.

In this sentence, the idea is:

1. first, they opened one pomegranate,
2. then they spent a long time eating it.

That completed, one-time action is why открыли is natural here.

Compare:

• мы открыли гранат = we opened the pomegranate / we cut it open
• мы открывали гранат = we were opening the pomegranate / used to open pomegranates / opened it repeatedly, depending on context

Yes. In Russian, открыть can be used for things that are physically opened up, not just doors, books, and shops.

With food, it can mean something like:

• open
• cut open
• break open

So открыли один гранат means they opened the pomegranate up so they could eat it. In English, cut open might sound more natural, but Russian открыть works fine here.

Один means one.

So один гранат literally means one pomegranate.

Russian often uses один when the speaker wants to emphasize that it was just one item, especially if that one item was shared. In this sentence, that makes sense: the whole family shared a single pomegranate.

Grammatically:

• один agrees with гранат
• гранат is masculine singular
• so the form is один

It is in the accusative singular, because it is the direct object of открыли.

However, for a masculine inanimate noun, the accusative singular looks the same as the nominative singular.

So:

• nominative: гранат
• accusative: гранат

That is why the form does not change.

Here it means pomegranate.

This is a very common learner question because the words are similar:

• гранат = pomegranate
• граната = grenade

They are different nouns, with different genders:

• гранат is masculine
• граната is feminine

So in this sentence, один гранат can only mean one pomegranate.

You could say just долго ели if the object were obvious from context, but его makes the sentence clearer and more explicit: they ate it.

Here его refers back to гранат.

So the structure is:

• открыли один гранат = opened one pomegranate
• ели его = ate it

This kind of pronoun is very normal in Russian when referring back to something already mentioned.

Here его is in the accusative, because it is the direct object of ели.

For the pronoun он, the form его can be:

• genitive
• accusative

In this sentence, it is accusative because it answers what did they eat? — его.

Because Russian uses the instrumental case in expressions like as a whole family, with the whole family, or all together as a family.

So:

• вся семья = the whole family (nominative, subject form)
• всей семьёй = as a whole family / with the whole family / all together as a family

In this sentence, всей семьёй describes how they were eating: they were doing it together, as one family group.

This is a very common Russian pattern:

• всем классом = as a whole class
• всей группой = as a whole group
• всей семьёй = as a whole family

Because both words have to match the instrumental-case phrase.

The base forms are:

• вся = whole, entire
• семья = family

In the instrumental singular feminine, they become:

• всей
• семьёй

So the phrase is fully declined:

• nominative: вся семья
• instrumental: всей семьёй

Also, семьёй is often written with ё, which helps show the correct pronunciation.

Yes. Долго means for a long time or a long time.

So:

• долго ели = ate for a long time

It tells you the action lasted a while. That fits the idea of eating a pomegranate slowly, probably because everyone was sharing it.

Yes, Russian word order is flexible, but this order is natural and neutral.

It goes:

1. После ужина = time frame
2. мы = subject
3. открыли один гранат = first action
4. и долго ели его всей семьёй = second action, with extra details

You could move things around for emphasis, for example:

• После ужина мы открыли один гранат и всей семьёй долго ели его.
• После ужина мы всей семьёй открыли один гранат и долго ели его.

These are possible, but the original sentence sounds straightforward and natural.

Because и is simply joining two verbs with the same subject:

• мы открыли
• (мы) ели

This is a normal coordinated structure, so no comma is needed.

A comma would usually appear only if there were separate clauses with more independence, extra information, or another reason for punctuation. Here it is just a simple we did X and did Y structure.

Yes. They are the same word and form.

• семьёй is the version with ё
• семьей is the version where ё is written as е

In printed Russian, ё is often replaced by е, but the pronunciation is still -йо́й here. For learners, the spelling семьёй is often more helpful because it shows the stress and pronunciation more clearly.