Au restaurant, Paul préfère les frites, alors que Marie choisit la salade.

Au restaurant means at the restaurant.

It is made from:

• à = at / to
• le restaurant = the restaurant

In French, à + le contracts to au:

• à le → au

So:

• au restaurant = at the restaurant

This opening phrase sets the scene, just like At the restaurant, ... in English.

Because in French, à + le normally must contract to au.

Common contractions:

• à + le → au
• à + les → aux
• de + le → du
• de + les → des

So you say:

• au restaurant
• not à le restaurant

The comma separates the introductory phrase from the main sentence.

• Au restaurant, = setting the context
• Paul préfère les frites... = the main statement

This is very similar to English:

• At the restaurant, Paul prefers fries...

The comma is natural and helps readability, though punctuation can sometimes vary depending on style.

Préfère means prefers.

It comes from the verb préférer = to prefer.

In this sentence:

• Paul préfère = Paul prefers

The accents are part of the correct spelling. French accents are not optional.

Here, notice two different accents:

• é in pré-
• è in -fère

This change happens in the conjugation of préférer:

• je préfère
• tu préfères
• il/elle préfère

So préfère is simply the correct he/she form of the verb.

French often uses an article where English might not.

So:

• les frites = literally the fries
• but in natural English, you often just say fries

French usually wants an article before nouns in cases like this:

• J’aime le café. = I like coffee.
• Elle mange une pomme. = She is eating an apple.
• Paul préfère les frites. = Paul prefers fries.

Here, les is the plural definite article, used with frites.

Because the nouns differ in number:

• la salade = singular feminine noun
• les frites = plural noun

Articles in French must match the noun:

• le = singular masculine
• la = singular feminine
• les = plural

So:

• la salade = the salad
• les frites = the fries

Even though English sometimes drops the, French usually keeps the article.

Alors que means something like:

• whereas
• while
• but, in a contrastive sense

In this sentence, it introduces a contrast between Paul’s choice and Marie’s choice:

• Paul prefers fries, whereas Marie chooses the salad.

It does not mean time here. It is not while in the sense of two actions happening simultaneously. It is while/whereas in the sense of in contrast.

Sometimes, yes, in terms of overall meaning. But grammatically, alors que is closer to whereas or while.

Compare:

• Paul préfère les frites, alors que Marie choisit la salade. = Paul prefers fries, whereas Marie chooses the salad.

Using but in English sounds natural:

• Paul prefers fries, but Marie chooses the salad.

However, in French, mais and alors que are not always interchangeable. Alors que often highlights a clearer contrast between two situations.

Choisit means chooses.

It comes from the verb choisir = to choose.

In this sentence:

• Marie choisit la salade = Marie chooses the salad

This is the il/elle/on form of the present tense:

• je choisis
• tu choisis
• il/elle choisit
• nous choisissons
• vous choisissez
• ils/elles choisissent

Because they come from different verbs, and French verbs are conjugated according to their verb group and subject.

Here:

• préfère comes from préférer
• choisit comes from choisir

Both are in the present tense and match a third-person singular subject:

• Paul préfère
• Marie choisit

The endings differ because the infinitives differ:

• many -er verbs have forms like -e
• many -ir verbs like choisir have forms like -it in il/elle

Because the phrase Au restaurant applies to the whole sentence.

It sets the context once:

• At the restaurant, Paul prefers fries, whereas Marie chooses the salad.

French, like English, does not need to repeat the location if it is already clear.

If you repeated it, it would sound heavier and less natural unless you wanted special emphasis.

Yes. Both main verbs are in the present tense:

• Paul préfère = Paul prefers
• Marie choisit = Marie chooses

French present tense can often correspond to several English possibilities depending on context:

• prefers / chooses
• sometimes is preferring / is choosing in rare contexts
• sometimes a more general habitual present

Here, the most natural interpretation is a simple present statement.

Because Paul and Marie are proper nouns. In French, proper names usually do not take an article.

So:

• Paul préfère...
• Marie choisit...

That works just like English:

• Paul prefers...
• Marie chooses...

In some informal regional usage, you may hear articles before names, but standard French normally does not use them here.

Yes, but the original order is very natural.

Original:

• Au restaurant, Paul préfère les frites, alors que Marie choisit la salade.

You could also say:

• Paul préfère les frites au restaurant, alors que Marie choisit la salade.

But that can slightly change the emphasis. Starting with Au restaurant is a nice way to frame the whole situation first.

French often uses this kind of fronted phrase for context:

• En été, ...
• Le matin, ...
• À Paris, ...

So the original sentence sounds smooth and natural.