When you want to say what had happened before something else in the past, you need to use the
pluperfect tense. It is formed by using the imperfect tense of avoir or être with the past participle. For example:
Je suis arrivé à l’aéroport mais j’avais oublié mon passeport. - I arrived at the airport (perfect tense) but I had forgotten (pluperfect) my passport.
Here is the pluperfect form of the verb manger in full:
J’avais mangé - I had eaten
Tu avais mangé - You had eaten
Il / Elle avait mangé - He / She had eaten
Nous avions mangé - We had eaten
Vous aviez mangé - You had eaten
Ils / Elles avaient mangé - They had eaten
Quand je suis rentré, ils avaient déjà mangé les chocolats. - When I got home, they had already eaten the chocolates.
There are of course some verbs such as aller, arriver, rester and partir which take être instead of
avoir. Here is the pluperfect form of partir in full:
J’étais parti(e) - I had left
Tu étais parti(e) - You had left
Il était parti - He had left
Elle était partie - She had left
Nous étions parti(e)s - We had left
Vous étiez parti(e)(s) - You had left
Ils étaient partis - They had left (m.)
Elles étaient parties - They had left (f.)
Il était parti sans moi. - He had left without me.
Note how the pluperfect is used in the following sentences:
Dans la Creuse, au centre de la France, je suis allé à un festival qui s’appelle la Saint-Cochon. - In the Creuse in central France I went to a festival called la Saint-Cochon.
À la fin de la soirée, j’étais fatigué. On avait dansé, on avait chanté et on avait joué aux jeux
avec les enfants. - At the end of the evening I was tired. We had danced, sung and played games with the children.
J’ai mangé des saucisses de porc. - Les habitants du village avaient préparé les saucisses
la veille. - I ate pork sausages. The inhabitants of the village had made the sausages the day before.