Marie s’inquiète quand le train est en retard.

s’ is the reflexive pronoun se, shortened before a vowel.

• se inquiète becomes s’inquiète
• It matches the subject Marie because Marie is third person singular

The full dictionary form is s’inquiéter, which means to worry or to become worried.

So:

• Marie s’inquiète = Marie worries / Marie gets worried

It is not usually translated literally as Marie worries herself in natural English, even though the French verb is reflexive.

In French, s’inquiéter is simply the normal way to say to worry in the sense of to be worried.

Compare:

• inquiéter quelqu’un = to worry someone
• s’inquiéter = to worry / to be worried

So:

• Le retard inquiète Marie. = The delay worries Marie.
• Marie s’inquiète. = Marie is worried / Marie worries.

A native English speaker often wonders why French uses a reflexive form here. The answer is: that is just how this meaning is commonly expressed in French.

s’inquiéter is the infinitive, the dictionary form: to worry.

In the sentence, the verb has to be conjugated because the subject is Marie:

• infinitive: s’inquiéter
• with Marie / il / elle / on: s’inquiète

So:

• Marie s’inquiète = correct
• Marie s’inquiéter = incorrect

The accent in inquiète is a grave accent: è.

It helps show the pronunciation of that syllable. In this form, the verb changes spelling from the infinitive:

• s’inquiéter
• je m’inquiète
• tu t’inquiètes
• il / elle s’inquiète

This kind of vowel change is common in French verbs.

Quand means when.

It introduces the time clause:

• quand le train est en retard = when the train is late

It works very much like English when in this sentence.

You could also sometimes use lorsque, which also means when, but quand is more common and more everyday here.

Le train means the train.

French often uses the definite article when talking about something specific, expected, or understood from context. Here it sounds like a particular train that matters in the situation.

• le train = the train
• un train = a train

If you said un train, it would sound less specific, as if any train being late causes the worry.

En retard is a fixed expression meaning late or behind schedule.

So:

• Le train est en retard. = The train is late.

French uses être en retard very often for people and things:

• Je suis en retard. = I am late.
• Le bus est en retard. = The bus is late.

Even though English often uses just is late, French usually uses the full expression est en retard.

Because en retard is used with être.

This is the standard pattern:

• être en retard = to be late

So in the sentence:

• le train est en retard

That is the normal, idiomatic way to say it in French.

You may also see related expressions like:

• avoir du retard = to be delayed / to have a delay

For example:

• Le train a du retard.

That also works, but le train est en retard is simpler and very common.

French often uses the present tense for general truths, habits, or repeated situations, just like English.

This sentence suggests a usual or typical situation:

• Marie s’inquiète quand le train est en retard.
• Marie worries when the train is late.

It does not have to mean it is happening right this second. It can describe what generally happens whenever that situation occurs.

Yes. It is a subordinate clause introduced by quand.

It has its own subject and verb:

• subject: le train
• verb: est

So the sentence has:

1. main clause: Marie s’inquiète
2. time clause: quand le train est en retard

This is very similar to English structure.

A rough pronunciation is:

• san-kee-et

A few useful points:

• s’ links smoothly into the next word because of the apostrophe
• inqui- sounds like in-kee
• -ète has an open eh sound because of è

You do not pronounce it as if there were a strong English kwy sound. The middle is closer to kee than to kwee-yet.

Yes, you can, but the nuance is a little different.

• Marie s’inquiète emphasizes the action or reaction of worrying
• Marie est inquiète emphasizes Marie’s state: she is worried/anxious

Both can fit, but s’inquiète often feels a bit more dynamic: she starts worrying or tends to worry when that happens.

Not here. Since this sentence describes a general present-time situation, the present tense is natural in both clauses.

French does not use a future tense after quand if the meaning is general or habitual like this.

For example, for a habitual idea:

• Je lis quand j’ai le temps. = I read when I have time.

So:

• Marie s’inquiète quand le train est en retard is completely normal.

No. The word order is very standard.

• Marie = subject
• s’inquiète = verb
• quand le train est en retard = time clause

French and English are quite similar here:

• Marie worries when the train is late.

So this is a good example of a sentence whose structure is straightforward, even though the reflexive verb may feel unfamiliar at first.