Nous avons eu du mal à dormir pendant la tempête, parce que le tonnerre était très fort.

Nous avons eu is the passé composé, which is often used for a completed situation in the past.

Here, avoir du mal à dormir means to have trouble sleeping, and nous avons eu du mal means we had trouble.

Why not nous avions?

• Nous avons eu du mal presents the trouble as a specific past event or situation.
• Nous avions du mal would use the imparfait, which would sound more like background, habit, or an ongoing past state.

In this sentence, the speaker is talking about one particular situation: during the storm, they had trouble sleeping.

Avoir du mal à + infinitive is a very common French expression meaning:

• to have trouble doing something
• to find it hard to do something

So:

• avoir du mal à dormir = to have trouble sleeping
• avoir du mal à comprendre = to have trouble understanding
• avoir du mal à se réveiller = to have trouble waking up

It is idiomatic, so it is best learned as a whole chunk.

In this expression, du mal is part of the fixed phrase avoir du mal à.

Literally, du is a partitive article, but in this expression you should not translate word by word. Just learn:

• avoir du mal à faire quelque chose = to have trouble doing something

So even though mal by itself often means badly or wrong, here du mal is a noun phrase meaning something like difficulty.

For example:

• J’ai du mal à lire sans lunettes. = I have trouble reading without glasses.

Because the expression is avoir du mal à + infinitive.

So the pattern is:

• avoir du mal à dormir
• avoir du mal à marcher
• avoir du mal à parler français

You cannot normally replace this à with de in this expression.

Because after à, French uses the infinitive form of the verb.

So:

• à dormir = to sleep
• à manger = to eat
• à travailler = to work

Dormi is a past participle, used in forms like:

• J’ai dormi = I slept / I have slept

But here the structure is not a compound tense. It is the expression avoir du mal à + infinitive, so dormir is required.

Here pendant means during.

So:

• pendant la tempête = during the storm

More generally, pendant can also be used for duration, often meaning for:

• J’ai dormi pendant deux heures. = I slept for two hours.

In this sentence, though, it clearly means during because it introduces the time period when the trouble happened.

French usually uses articles more often than English does.

In English, we often say:

• during the storm

French also needs the article here:

• pendant la tempête

You generally would not say pendant tempête.

Also, tempête is a feminine noun, so it takes la.

Parce que means because and introduces the reason.

So:

• parce que le tonnerre était très fort = because the thunder was very loud

This is the most common everyday way to say because in French.

You may also see car, which can also mean because, but parce que is usually more common in normal spoken French.

Était is the imparfait of être, and it is used here to describe a background condition in the past: the thunder was very loud.

The imparfait is commonly used for:

• descriptions
• ongoing states
• background information

That fits this sentence well: the thunder being loud is the condition that explains why they could not sleep easily.

If you said le tonnerre a été très fort, it would sound more like a completed fact or event, and it is less natural in this kind of descriptive context.

Because fort agrees with le tonnerre, which is masculine singular.

• le tonnerre = masculine singular
• so the adjective is fort

If the noun were feminine, you would usually add -e:

• la musique était forte = the music was loud

Here:

• le tonnerre était très fort = the thunder was very loud

Yes, fort can mean different things depending on context.

It often means:

• strong
• powerful
• loud

With sounds, fort often means loud.

Examples:

• une voix forte = a loud voice
• la musique est trop forte = the music is too loud

So in this sentence, le tonnerre était très fort naturally means the thunder was very loud.

In French, adverbs like très usually come before the adjective they modify.

So:

• très fort = very loud
• très grand = very tall / very big
• très difficile = very difficult

That placement is normal and direct.

Yes. In everyday spoken French, on is very often used instead of nous.

So these both work:

• Nous avons eu du mal à dormir...
• On a eu du mal à dormir...

The second one is more conversational and common in speech.

The first one is perfectly correct and slightly more formal or neutral.

It can feel tricky because there are several vowel sounds together.

Roughly:

• nous sounds like noo
• avons sounds roughly like ah-von
• eu sounds like the French vowel in eu / œu, which English does not have exactly

In connected speech, nous avons eu is often pronounced smoothly, with liaison after nous:

• nous avons → the s links to the next word, so it sounds like noo-zavon
• then eu follows

So you may hear something like:

• noo-zavon-uh / ø

The most important thing for a learner is recognizing it as the passé composé of avoir:

• j’ai eu
• tu as eu
• il a eu
• nous avons eu

It looks repetitive, but it is completely normal in French.

Yes, that would also be natural, but it changes the meaning slightly.

• la tempête = the storm
• l’orage = the thunderstorm / storm with thunder and lightning

Since the sentence specifically mentions thunder, orage would fit well too. But tempête is broader and can refer to a storm in general.

So both can work, depending on what kind of weather the speaker wants to emphasize.