Learn Hardcore French: Passer la frontière la nuit peut être dangereux, alors nous prenons le train le matin. - Crossing the border at night can be dangerous, so we take the train in the morning.

Passer la frontière la nuit peut être dangereux, alors nous prenons le train le matin.

Crossing the border at night can be dangerous, so we take the train in the morning.

Breakdown of Passer la frontière la nuit peut être dangereux, alors nous prenons le train le matin.

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Questions & Answers about Passer la frontière la nuit peut être dangereux, alors nous prenons le train le matin.

Why does the sentence start with Passer (the infinitive) instead of using a noun, like Le passage de la frontière la nuit?

French often uses the infinitive as the subject of a sentence, where English uses an -ing form.

Passer la frontière la nuit peut être dangereux
= Crossing the border at night can be dangerous.

Here, Passer is an infinitive functioning as a noun-like subject, just as Crossing is a gerund in English.

You could say:

Le fait de passer la frontière la nuit peut être dangereux.
(Literally: The fact of crossing the border at night can be dangerous.)

This version is more formal or heavier. The original with the bare infinitive is more natural and common in everyday French.

Why is it la frontière and not une frontière?

Using la frontière (definite article) suggests a specific, known, or contextually understood border – or the border in general in that situation.

Passer la frontière la nuit peut être dangereux.
= Crossing the border at night can be dangerous.

If you said une frontière, it would sound like “some border or other” and less like a general statement about the border in question. In French, the definite article is often used where English might omit it or use no article when speaking in general:

La vie est belle. = Life is beautiful.
La frontière, in context, can similarly mean “the border (we are talking about / in general).

What exactly does passer la frontière mean? Is it different from traverser or franchir?

Passer la frontière is the most common everyday way to say “to cross the border.”

passer la frontière – neutral, very common: to go through / cross the border
franchir la frontière – a bit more formal or literary, also means to cross, to get across
traverser la frontière – possible, but much less common; traverser is more natural with spaces or areas (e.g. traverser la rue, traverser un parc).

In normal speech, if you talk about crossing a national border, passer la frontière is the default choice.

Why is it la nuit but le matin? How do these work in time expressions?

Both are using the definite article, and both correspond to English “at night” / “in the morning”:

la nuit = at night / during the night
le matin = in the morning

French uses le / la for recurring or generic times of day:

Le matin, je prends un café. = In the mornings, I have a coffee.
La nuit, il fait froid ici. = At night, it’s cold here.

So in your sentence:

Passer la frontière la nuit = Crossing the border at night
nous prenons le train le matin = we take the train in the morning

You might also see:

la nuit vs dans la nuit
- la nuit = generally at night
- dans la nuit = during the night (often a more specific night, or emphasizing duration/when something happened)

Why is dangereux used here, and why doesn’t it change form? Should it be dangereuse?

In peut être dangereux, dangereux is an adjective describing the entire action Passer la frontière la nuit.

That whole infinitive phrase is treated as a masculine singular subject in French. So the adjective must be masculine singular:

Passer la frontière la nuit peut être dangereux.

For most adjectives, the masculine singular form is the “base form.”
Dangereux is a bit special because:

Masculine singular: dangereux
Masculine plural: dangereux (same spelling)
Feminine singular: dangereuse
Feminine plural: dangereuses

If the subject were clearly feminine, you’d get dangereuse:

Cette route peut être dangereuse.
(This road can be dangerous. – route is feminine.)

But for an infinitive phrase, you stick with masculine singular: dangereux.

How does peut work here? Why isn’t there a separate word for “can,” like in English?

French uses the verb pouvoir to express can / may / to be able to.

In your sentence:

peut is 3rd person singular of pouvoir (il/elle/on peut).
The subject is the whole idea Passer la frontière la nuit.

So structurally:

Passer la frontière la nuit (subject)
peut (can)
être dangereux (be dangerous)

Literally: To cross the border at night can be dangerous.

French doesn’t need a separate word for “can”; peut already means can here.

Compare:

Nager ici peut être dangereux. = Swimming here can be dangerous.
Conduire vite peut être risqué. = Driving fast can be risky.

What exactly does alors mean here? Is it the same as donc or puis?

In this sentence, alors means so / therefore:

… peut être dangereux, alors nous prenons le train…
= … can be dangerous, so we take the train…

Some nuances:

alors – very common, spoken, often used like English so in conversation.
donc – also means so / therefore, can sound a bit more logical/structured, but is also common in speech.
puis – means then / afterwards, used for sequencing events, not cause and consequence.

You could say:

… peut être dangereux, donc nous prenons le train le matin.
This is also correct and quite natural.

But puis would be wrong here, because you’re expressing a reason/result, not just a time sequence.

Why is it nous prenons le train and not a future form like nous prendrons le train?

Nous prenons le train le matin can express:

A habitual action:
- We (normally) take the train in the morning.
A planned future, especially when the time is mentioned:
- We’re taking the train in the morning.

French often uses the present tense for near-future plans when there is a time expression (le matin, demain, ce soir, etc.).

If you say:

Nous prendrons le train le matin.

that is a simple future and is correct, but it can sound a bit more formal or more neutral; nous prenons le train le matin feels more like a usual choice/habit or a decided plan.

In very natural spoken French, you’d also often hear:

On prend le train le matin. (more colloquial than nous prenons)

Why is it le train and not un train or en train?

Each form expresses something slightly different:

prendre le train = to take the train (this means to travel by train; the definite article is standard here)
prendre un train = to take a train (a particular train, often when choosing among several)
aller en train = to go by train (emphasizes the means of transport).

In your sentence:

nous prenons le train le matin
is the usual, idiomatic way to say we take the train in the morning / we travel by train in the morning.

Using le doesn’t mean one specific physical train is known; it’s just part of the fixed pattern prendre le train.

Can la nuit move to another position in the sentence? For example, could you say La nuit, passer la frontière peut être dangereux?

Yes, time expressions like la nuit are relatively flexible in French, just like in English. All of these are grammatical, with slightly different emphasis:

Passer la frontière la nuit peut être dangereux.
Neutral, standard order.
La nuit, passer la frontière peut être dangereux.
Emphasizes at night at the beginning: At night, crossing the border can be dangerous.
Passer la frontière peut être dangereux la nuit.
Also possible; la nuit is added at the end, slightly stressing that the danger is specifically at night.

The original version is probably the most natural-sounding and balanced, but the others are acceptable and sometimes used for stylistic variation or emphasis.