Usage note : when

when can very often be translated by quand in time expressions :

when did she leave?

= quand est-ce qu’elle est partie? or elle est partie quand? or quand est-elle partie?

Note that in questions quand on its own requires inversion of the verb and subject :

when are they arriving?

= quand arrivent-ils?

but when followed by est-ce que needs no inversion : quand est-ce qu’ils arrivent?

Occasionally a more precise time expression is used in French :

when’s your birthday?

= quelle est la date de ton anniversaire?

when did he set off?

= à quelle heure est-il parti?

Remember that the future tense is used after quand if future time is implied :

tell him when you see him

= dis-le-lui quand tu le verras

It is often possible to give a short neat translation for a when clause if there is no change of subject in the sentence :

when I was very young, I lived in Normandy

= tout jeune, j’habitais en Normandie

when he was leaving, he asked for my address

= en partant, il m’a demandé mon adresse

In expressions such as the day when, the year when, où is used :

the day when we got married

= le jour où nous nous sommes mariés

For examples of the above and further uses of when, see the entry when.

Big English-French dictionary. 2003.