Imparfait v Passé Composé

Question

This week's Weekend Workout (31-08-2018) has a question and answer as detailed below.
The translation for 'we arrived' is given in the imparfait but surely it should be in the Passé composé as they arrived only 'once' and not as the imparfait implies 'used to arrive' meaning they arrived on a regular basis i.e. more than just on the one occasion.
Could you please explain.
When we arrived in the changing rooms,
Quand nous arrivions dans les vestiaires,

Accepted Answer

Hi Stewart, 
I have had a look at the whole text and it starts "Quand ma fille était petite ..." which indicates you are going back to a period in the past which describes things you would habitually do and the imparfait is used for this.
It gives the impression of going back in time, zooming in on a particular period in one's life. My biopic would be something like: 
"Quand j'étais petite, j'habitais Versailles. Nous avions un appartement rue Champ Lagarde. Il n'y avait pas beaucoup de circulation dans la rue, et je pouvais jouer au jokari et aux patins à roulettes sur la rue même, ce qui serait impossible maintenant. Pendant les vacances d'été mes copines d'école et moi allions à la piscine Montbauron où nous passions de bons moments..."
If you are still confused, take a look at the following lesson -
https://french.kwiziq.com/revision/grammar/l-imparfait-usage-expressing-habits-or-repeated-actions-in-the-past-imperfect-tense
Hope this helps!

Answer

Hi Stewart, 
Is there an action in the passé composé afterwards?

Answer

Hi Cécile
The quiz for this complete sentence was asked in 3 seperate parts:
PART 1 
When we arrived in the changing rooms,  (Answer: Quand nous arrivions dans les vestiaires,)
PART 2 
I dressed her       (Answer: je l’habillais)

PART 3
then I put her floaties [inflatable armbands] on her.       (Answer: puis je lui enfilais ses brassards.)

Answer

Thanks Cécile,
I can now see that I had misunderstood the question which actually meant 'every time' we arrived at the changing room (hense use of the imparfait) and not 'when we arrived' (on the one occasion only).