Мне нравится, когда в пьесе есть живой диалог, а не только длинные реплики одного героя.

Because нравиться works differently from English to like.

In Russian, the thing that is pleasing is the grammatical subject, and the person who experiences the feeling goes in the dative case.

So:

• Мне нравится диалог = The dialogue is pleasing to me = I like the dialogue
• Я нравлюсь would mean I am pleasing / I am liked

That is why the sentence starts with мне нравится: I like...

The verb is singular because the main idea being liked is treated as one general situation:

• когда в пьесе есть живой диалог, а не только длинные реплики одного героя

This whole когда... clause functions like one thing: the fact that there is lively dialogue...

Russian often uses singular нравится when what follows is a clause or one overall situation.

Compare:

• Мне нравится этот диалог. — singular noun
• Мне нравится, когда актеры говорят естественно. — whole clause/situation

Yes, когда literally means when, but in sentences like this it often means when / whenever / the situation where.

So here:

• Мне нравится, когда... = I like it when...

It introduces the kind of situation the speaker enjoys.

This is a very common Russian pattern:

• Мне нравится, когда идет дождь. — I like it when it rains.
• Мне не нравится, когда люди опаздывают. — I don’t like it when people are late.

Because когда в пьесе есть живой диалог... is a subordinate clause.

Russian normally separates subordinate clauses with commas, including clauses introduced by:

• когда — when
• если — if
• потому что — because
• что — that

So:

• Мне нравится, когда...

needs a comma before когда.

В пьесе means in the play.

Here пьеса is in the prepositional case because it follows в in the meaning of location:

• пьеса → dictionary form
• в пьесе → in the play

This is a very common pattern:

• в книге — in the book
• в фильме — in the film
• в рассказе — in the story

Here есть means there is / there are.

So:

• в пьесе есть живой диалог = there is lively dialogue in the play

Russian often omits есть in the present tense when simply saying X is Y, but it is commonly used when expressing existence/presence:

• Он актер. — He is an actor.
• В пьесе есть актеры. — There are actors in the play.

Could it be omitted here? Sometimes in casual speech Russians may drop it, but есть sounds natural and clear because the idea is specifically there is lively dialogue.

Yes, живой literally means alive / living, but in many contexts it has a broader meaning:

• lively
• natural
• vivid
• realistic
• dynamic

So живой диалог is not literally a living dialogue. It means something like:

• lively dialogue
• natural-sounding dialogue
• realistic, engaging dialogue

This is a common figurative use of живой in Russian.

А here adds contrast: but / rather than / as opposed to.

So:

• живой диалог, а не только длинные реплики одного героя

means:

• lively dialogue, and not just long lines from one character
• or more naturally: lively dialogue rather than just long speeches by one character

Without а, the sentence would lose some of that contrast.
Russian often uses а не to set one thing against another:

• Это важно, а не смешно. — It’s important, not funny.
• Я хочу чай, а не кофе. — I want tea, not coffee.

Here не только means not only / not just, and а helps mark the opposition.

Because реплики means lines / remarks / utterances, and the sentence is talking about multiple bits of speech from one character.

In literary or theatrical language:

• реплика = a character’s line
• реплики = lines

So длинные реплики одного героя means something like:

• long lines from one character
• lengthy speeches by one character

Russian uses the plural because the idea is not one single line, but a pattern of speech in the play.

Because реплики одного героя means the lines of one character or lines from one character, and after a noun like реплики Russian often uses the genitive case to show relation or belonging.

So:

• один герой = one character (nominative)
• одного героя = of one character / from one character (genitive)

This is similar to:

• страницы книги — pages of the book
• слова учителя — the teacher’s words
• реплики героя — the character’s lines

Here одного agrees with героя in the genitive singular.

Yes. Although герой can mean hero, in literary and theatrical contexts it very often means character.

So in a sentence about a play:

• герой пьесы = a character in the play

It does not necessarily imply that the person is heroic in the English sense.

Russian word order is flexible, but the original order sounds natural and balanced.

Original:

• Мне нравится, когда в пьесе есть живой диалог, а не только длинные реплики одного героя.

This order presents:

1. the speaker’s reaction — Мне нравится
2. the situation — когда в пьесе есть...
3. the contrast — а не только...

You could rearrange parts, but the nuance or emphasis would change. For example:

• Мне нравится, когда есть живой диалог в пьесе...
  This is possible, but a little less natural than когда в пьесе есть...

Russian often uses word order to highlight focus, but the original version is a very standard, neutral way to say it.

Not perfectly.

• диалог = dialogue, especially in literature, theater, film, or a structured exchange between speakers
• разговор = conversation, talk

Because the sentence is about a play (пьеса), диалог is the best choice. It fits the language of drama and writing.

So:

• живой диалог sounds natural for discussing a play
• живой разговор would sound more like a real-life conversation

It is mostly neutral, with a slightly literary feel because of words like:

• пьеса — play
• диалог — dialogue
• реплики — lines/remarks
• герой — character

It would sound natural in conversation, in a review, or in a class discussion about literature or theater. It is not overly formal, but it is more polished than very casual everyday speech.